<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:href="nx-20200131.xsd#CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:href="nx-20200131.xsd#CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementOfStockholdersEquity" xlink:href="nx-20200131.xsd#CondensedConsolidatedStatementOfStockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementOfStockholdersEquityParenthetical" xlink:href="nx-20200131.xsd#CondensedConsolidatedStatementOfStockholdersEquityParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfCashFlowUnaudited" xlink:href="nx-20200131.xsd#CondensedConsolidatedStatementsOfCashFlowUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfComprehensiveIncomeLossUnaudited" xlink:href="nx-20200131.xsd#CondensedConsolidatedStatementsOfComprehensiveIncomeLossUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfIncomeLossUnaudited" xlink:href="nx-20200131.xsd#CondensedConsolidatedStatementsOfIncomeLossUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfIncomeLossUnauditedParenthetical" xlink:href="nx-20200131.xsd#CondensedConsolidatedStatementsOfIncomeLossUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/Contingencies" xlink:href="nx-20200131.xsd#Contingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/ContingenciesDetails" xlink:href="nx-20200131.xsd#ContingenciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DebtAndCapitalLeaseObligations" xlink:href="nx-20200131.xsd#DebtAndCapitalLeaseObligations" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DebtAndCapitalLeaseObligationsDetail" xlink:href="nx-20200131.xsd#DebtAndCapitalLeaseObligationsDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DebtAndCapitalLeaseObligationsTables" xlink:href="nx-20200131.xsd#DebtAndCapitalLeaseObligationsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DocumentAndEntityInformation" xlink:href="nx-20200131.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/EarningsPerShare" xlink:href="nx-20200131.xsd#EarningsPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/EarningsPerShareDetail" xlink:href="nx-20200131.xsd#EarningsPerShareDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/EarningsPerShareEarningsPerShareTables" xlink:href="nx-20200131.xsd#EarningsPerShareEarningsPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/FairValueMeasurementOfAssetsAndLiabilities" xlink:href="nx-20200131.xsd#FairValueMeasurementOfAssetsAndLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/FairValueMeasurementOfAssetsAndLiabilitiesDetails" xlink:href="nx-20200131.xsd#FairValueMeasurementOfAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/FairValueMeasurementOfAssetsAndLiabilitiesTables" xlink:href="nx-20200131.xsd#FairValueMeasurementOfAssetsAndLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssets" xlink:href="nx-20200131.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssetsGoodwillDetails" xlink:href="nx-20200131.xsd#GoodwillAndIntangibleAssetsGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssetsIdentifiableIntangibleAssetsDetail" xlink:href="nx-20200131.xsd#GoodwillAndIntangibleAssetsIdentifiableIntangibleAssetsDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="nx-20200131.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/IncomeTaxes" xlink:href="nx-20200131.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/IncomeTaxesDetail" xlink:href="nx-20200131.xsd#IncomeTaxesDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/IncomeTaxesIncomeTaxTables" xlink:href="nx-20200131.xsd#IncomeTaxesIncomeTaxTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/Inventories" xlink:href="nx-20200131.xsd#Inventories" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/InventoriesDetail" xlink:href="nx-20200131.xsd#InventoriesDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/InventoriesTables" xlink:href="nx-20200131.xsd#InventoriesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/Leases" xlink:href="nx-20200131.xsd#Leases" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesAdditionalInformationDetails" xlink:href="nx-20200131.xsd#LeasesAdditionalInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:href="nx-20200131.xsd#LeasesFutureMinimumLeasePaymentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesLeaseCostsDetails" xlink:href="nx-20200131.xsd#LeasesLeaseCostsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesLeaseRelatedAssetsAndLiabilitiesDetails" xlink:href="nx-20200131.xsd#LeasesLeaseRelatedAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesPresentMaturityOfLeaseLiabilitiesDetails" xlink:href="nx-20200131.xsd#LeasesPresentMaturityOfLeaseLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesSupplementalCashFlowInformationDetails" xlink:href="nx-20200131.xsd#LeasesSupplementalCashFlowInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesTables" xlink:href="nx-20200131.xsd#LeasesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/LeasesWeightedAverageRemainingLeaseTermsAndWeightedAverageDiscountRatesDetails" xlink:href="nx-20200131.xsd#LeasesWeightedAverageRemainingLeaseTermsAndWeightedAverageDiscountRatesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentation" xlink:href="nx-20200131.xsd#NatureOfOperationsAndBasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentationDetails" xlink:href="nx-20200131.xsd#NatureOfOperationsAndBasisOfPresentationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentationSummaryOfProductSalesDetails" xlink:href="nx-20200131.xsd#NatureOfOperationsAndBasisOfPresentationSummaryOfProductSalesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentationTables" xlink:href="nx-20200131.xsd#NatureOfOperationsAndBasisOfPresentationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NewAccountingGuidanceAdopted" xlink:href="nx-20200131.xsd#NewAccountingGuidanceAdopted" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NewAccountingGuidanceAdoptedDetails" xlink:href="nx-20200131.xsd#NewAccountingGuidanceAdoptedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/OtherIncomeExpense" xlink:href="nx-20200131.xsd#OtherIncomeExpense" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseDetail" xlink:href="nx-20200131.xsd#OtherIncomeExpenseDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseTables" xlink:href="nx-20200131.xsd#OtherIncomeExpenseTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/RetirementPlans" xlink:href="nx-20200131.xsd#RetirementPlans" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/RetirementPlansDetail" xlink:href="nx-20200131.xsd#RetirementPlansDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/RetirementPlansTables" xlink:href="nx-20200131.xsd#RetirementPlansTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationDetails" xlink:href="nx-20200131.xsd#SegmentInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationGoodwillBySegmentDetails" xlink:href="nx-20200131.xsd#SegmentInformationGoodwillBySegmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationNotes" xlink:href="nx-20200131.xsd#SegmentInformationNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationReconcilliationOfOperatingLossToNetIncomeDetails" xlink:href="nx-20200131.xsd#SegmentInformationReconcilliationOfOperatingLossToNetIncomeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationSegmentReportingInformationDetails" xlink:href="nx-20200131.xsd#SegmentInformationSegmentReportingInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationTables" xlink:href="nx-20200131.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensation" xlink:href="nx-20200131.xsd#StockBasedCompensation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationDetail" xlink:href="nx-20200131.xsd#StockBasedCompensationDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceRestrictedStockUnitsDetails" xlink:href="nx-20200131.xsd#StockBasedCompensationPerformanceRestrictedStockUnitsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceShareAwardsDetails" xlink:href="nx-20200131.xsd#StockBasedCompensationPerformanceShareAwardsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockAwardsDetails" xlink:href="nx-20200131.xsd#StockBasedCompensationRestrictedStockAwardsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockUnitsDetails" xlink:href="nx-20200131.xsd#StockBasedCompensationRestrictedStockUnitsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationStockOptionsDetails" xlink:href="nx-20200131.xsd#StockBasedCompensationStockOptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTables" xlink:href="nx-20200131.xsd#StockBasedCompensationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTreasurySharesDetails" xlink:href="nx-20200131.xsd#StockBasedCompensationTreasurySharesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/WarrantyObligations" xlink:href="nx-20200131.xsd#WarrantyObligations" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/WarrantyObligationsDetail" xlink:href="nx-20200131.xsd#WarrantyObligationsDetail" xlink:type="simple" />
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/WarrantyObligationsTables" xlink:href="nx-20200131.xsd#WarrantyObligationsTables" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementOfStockholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_A902A488457F95E47CBE31A19EFC5E32" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_9F9C13331A5DBAF7B40531A19EFAE30F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_A902A488457F95E47CBE31A19EFC5E32" xlink:to="loc_us-gaap_StatementTable_9F9C13331A5DBAF7B40531A19EFAE30F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_6E79F8CA691C9CFBCF4031A19EFA6872" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_9F9C13331A5DBAF7B40531A19EFAE30F" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_6E79F8CA691C9CFBCF4031A19EFA6872" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6E79F8CA691C9CFBCF4031A19EFA6872" xlink:to="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6E79F8CA691C9CFBCF4031A19EFA6872" xlink:to="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_F7FA445F8E77C63501A531A19EFB25EE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:to="loc_us-gaap_CommonStockMember_F7FA445F8E77C63501A531A19EFB25EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_3A3CAC8483CE44D54EFD31A19EFBEB6E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_3A3CAC8483CE44D54EFD31A19EFBEB6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_CC5E29500EC27AF4A63E31A19EFB6E1C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:to="loc_us-gaap_RetainedEarningsMember_CC5E29500EC27AF4A63E31A19EFB6E1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_A6C41B842445AECAFCEE31A19EFBDA36" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_A6C41B842445AECAFCEE31A19EFBDA36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_3901044D20C70E27832C31A19EFBA14A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_A9913C1611A324E0BED931A19EFAC2A8" xlink:to="loc_us-gaap_TreasuryStockMember_3901044D20C70E27832C31A19EFBA14A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_A902A488457F95E47CBE31A19EFC5E32" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_175C656BD31260CC058131A19EFCF6CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_StockholdersEquity_175C656BD31260CC058131A19EFCF6CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_387D4CDCFA39E4869EB131A19EFD29FC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_NetIncomeLoss_387D4CDCFA39E4869EB131A19EFD29FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_0852805202AC720C78E731A19EFD50A8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_0852805202AC720C78E731A19EFD50A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DividendsCommonStockCash" xlink:label="loc_us-gaap_DividendsCommonStockCash_0BD54EB4B55C2DDC40B831A19EFDDA5F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_DividendsCommonStockCash_0BD54EB4B55C2DDC40B831A19EFDDA5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_3E61666DEE5ADCA4D2B731A19F02AFFF" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_3E61666DEE5ADCA4D2B731A19F02AFFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationAbstract_4CC356676A3FCB1A6B1931A19F029C8F" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_ShareBasedCompensationAbstract_4CC356676A3FCB1A6B1931A19F029C8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_7772860461ED0DC8397431A19F0316A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_4CC356676A3FCB1A6B1931A19F029C8F" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_7772860461ED0DC8397431A19F0316A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_F5CBA0BC28C49FA3834931A19F039CC5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_4CC356676A3FCB1A6B1931A19F029C8F" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_F5CBA0BC28C49FA3834931A19F039CC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_5A2AC6C80040C52CCF8131A19F039D56" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_4CC356676A3FCB1A6B1931A19F029C8F" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_5A2AC6C80040C52CCF8131A19F039D56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityOther" xlink:label="loc_us-gaap_StockholdersEquityOther_B39A0ABD3217CFE5516F31A19F03E7FE" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_32C5C8B337A3B72A53BE31A19EFC02CC" xlink:to="loc_us-gaap_StockholdersEquityOther_B39A0ABD3217CFE5516F31A19F03E7FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_FD035AFF6F6A029F08EA31A19F04914B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_A902A488457F95E47CBE31A19EFC5E32" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_FD035AFF6F6A029F08EA31A19F04914B" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_StockIssuedDuringPeriodTreasurySharesPerformanceSharesVested" xlink:label="loc_nx_StockIssuedDuringPeriodTreasurySharesPerformanceSharesVested_E6720B615B320F2BB6D031A19F04447B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_A902A488457F95E47CBE31A19EFC5E32" xlink:to="loc_nx_StockIssuedDuringPeriodTreasurySharesPerformanceSharesVested_E6720B615B320F2BB6D031A19F04447B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementOfStockholdersEquityParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfCashFlowUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfComprehensiveIncomeLossUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfIncomeLossUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsOfIncomeLossUnauditedParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/Contingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/ContingenciesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DebtAndCapitalLeaseObligations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DebtAndCapitalLeaseObligationsDetail" xlink:type="extended">
    <link:loc xlink:href="nx-20200131.xsd#nx_DebtDisclosureLineItems" xlink:label="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:type="locator" />
    <link:loc xlink:href="nx-20200131.xsd#nx_DebtDisclosureTable" xlink:label="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_232D3C09721CBA76450AABE17B1A6F6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_232D3C09721CBA76450AABE17B1A6F6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_DFD50648DD80F8D5B390ABE17B1AF07C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_232D3C09721CBA76450AABE17B1A6F6A" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_DFD50648DD80F8D5B390ABE17B1AF07C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_DFD50648DD80F8D5B390ABE17B1AF07C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_232D3C09721CBA76450AABE17B1A6F6A" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_DFD50648DD80F8D5B390ABE17B1AF07C" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_InterestRateScenarioAxis" xlink:label="loc_nx_InterestRateScenarioAxis_21297182391466976630ABE17B1B3958" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_nx_InterestRateScenarioAxis_21297182391466976630ABE17B1B3958" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_InterestRateScenarioDomain" xlink:label="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nx_InterestRateScenarioAxis_21297182391466976630ABE17B1B3958" xlink:to="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6_default" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_InterestRateScenarioDomain" xlink:label="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nx_InterestRateScenarioAxis_21297182391466976630ABE17B1B3958" xlink:to="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_LessThanOneandOneHalfLeverageRatioMember" xlink:label="loc_nx_LessThanOneandOneHalfLeverageRatioMember_C5A3E9D8370A4804209DABE17B1B906B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6" xlink:to="loc_nx_LessThanOneandOneHalfLeverageRatioMember_C5A3E9D8370A4804209DABE17B1B906B" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember" xlink:label="loc_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_00CB2D085D8EB10A3012ABE17B1BBD2F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6" xlink:to="loc_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_00CB2D085D8EB10A3012ABE17B1BBD2F" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember" xlink:label="loc_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_D6010DF87CA873BA8743ABE17B1BE61F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6" xlink:to="loc_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_D6010DF87CA873BA8743ABE17B1BE61F" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_GreaterThanThreeLeverageRatioMember" xlink:label="loc_nx_GreaterThanThreeLeverageRatioMember_B1A5A0B45DD684029226ABE17B1C72BB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_034C7DFF6ECE303E8E41ABE17B1B5AB6" xlink:to="loc_nx_GreaterThanThreeLeverageRatioMember_B1A5A0B45DD684029226ABE17B1C72BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionAxis" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_EF41CFD3A7CF830EA6A4ABE17B1C23E3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_EF41CFD3A7CF830EA6A4ABE17B1C23E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_73F6DD7317AB9B7E37CAABE17B1CF71F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_EF41CFD3A7CF830EA6A4ABE17B1C23E3" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_73F6DD7317AB9B7E37CAABE17B1CF71F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_73F6DD7317AB9B7E37CAABE17B1CF71F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_EF41CFD3A7CF830EA6A4ABE17B1C23E3" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_73F6DD7317AB9B7E37CAABE17B1CF71F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_6BF3D4C7A85C64B14E3AABE17B1C3A9B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_srt_RangeAxis_6BF3D4C7A85C64B14E3AABE17B1C3A9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_C3EB92E97AA035B3882AABE17B1C8276_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6BF3D4C7A85C64B14E3AABE17B1C3A9B" xlink:to="loc_srt_RangeMember_C3EB92E97AA035B3882AABE17B1C8276_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_C3EB92E97AA035B3882AABE17B1C8276" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6BF3D4C7A85C64B14E3AABE17B1C3A9B" xlink:to="loc_srt_RangeMember_C3EB92E97AA035B3882AABE17B1C8276" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_F916FCAACE75223B3812ABE17B1DEA66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_C3EB92E97AA035B3882AABE17B1C8276" xlink:to="loc_srt_MinimumMember_F916FCAACE75223B3812ABE17B1DEA66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_676345ED34E7DA9AE999ABE17B1D2440" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_C3EB92E97AA035B3882AABE17B1C8276" xlink:to="loc_srt_MaximumMember_676345ED34E7DA9AE999ABE17B1D2440" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_4B760D98D57C0201F86DABE17B1D3985" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_us-gaap_VariableRateAxis_4B760D98D57C0201F86DABE17B1D3985" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_C15D97EB9F11552BA6AEABE17B1D831E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_4B760D98D57C0201F86DABE17B1D3985" xlink:to="loc_us-gaap_VariableRateDomain_C15D97EB9F11552BA6AEABE17B1D831E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_C15D97EB9F11552BA6AEABE17B1D831E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_4B760D98D57C0201F86DABE17B1D3985" xlink:to="loc_us-gaap_VariableRateDomain_C15D97EB9F11552BA6AEABE17B1D831E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaap_BaseRateMember_814ACF1CA44595AF27CAABE17B1DD7D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_C15D97EB9F11552BA6AEABE17B1D831E" xlink:to="loc_us-gaap_BaseRateMember_814ACF1CA44595AF27CAABE17B1DD7D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_9728F6A09EC14CEEFFDDABE17B1E2F68" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_C15D97EB9F11552BA6AEABE17B1D831E" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_9728F6A09EC14CEEFFDDABE17B1E2F68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_89554D5A952FE612E7DCABE17B1E90FB" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_us-gaap_CreditFacilityAxis_89554D5A952FE612E7DCABE17B1E90FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_89554D5A952FE612E7DCABE17B1E90FB" xlink:to="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_89554D5A952FE612E7DCABE17B1E90FB" xlink:to="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_A2018CreditFacilityMember" xlink:label="loc_nx_A2018CreditFacilityMember_198F430AFA9FA88604A4ABE17B1E45A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7" xlink:to="loc_nx_A2018CreditFacilityMember_198F430AFA9FA88604A4ABE17B1E45A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_827C68FCCD88690EAB24ABE17B1FDEF4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_827C68FCCD88690EAB24ABE17B1FDEF4" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_TermLoanFacilityMember" xlink:label="loc_nx_TermLoanFacilityMember_5573EC6A22DCCC126D01ABE17B1F467F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_DDDE126CB75F563FE433ABE17B1EFBF7" xlink:to="loc_nx_TermLoanFacilityMember_5573EC6A22DCCC126D01ABE17B1F467F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_182E703F0D5B7200CB61ABE17B1F1F81" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_182E703F0D5B7200CB61ABE17B1F1F81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_35349FD67669A289A23CABE17B1F1D92_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_182E703F0D5B7200CB61ABE17B1F1F81" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_35349FD67669A289A23CABE17B1F1D92_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_35349FD67669A289A23CABE17B1F1D92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_182E703F0D5B7200CB61ABE17B1F1F81" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_35349FD67669A289A23CABE17B1F1D92" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_82614342041B7BDAD2E7ABE17B1FF321" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_dei_LegalEntityAxis_82614342041B7BDAD2E7ABE17B1FF321" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_89B26ECF555D20839824ABE17B1F6338_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_82614342041B7BDAD2E7ABE17B1FF321" xlink:to="loc_dei_EntityDomain_89B26ECF555D20839824ABE17B1F6338_default" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_89B26ECF555D20839824ABE17B1F6338" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_82614342041B7BDAD2E7ABE17B1FF321" xlink:to="loc_dei_EntityDomain_89B26ECF555D20839824ABE17B1F6338" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_E2CE1B86880B0FAC1C19ABE17B209968" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_DebtDisclosureTable_012FF775C909CAE4F994ABE17B19632C" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_E2CE1B86880B0FAC1C19ABE17B209968" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E2CE1B86880B0FAC1C19ABE17B209968" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E2CE1B86880B0FAC1C19ABE17B209968" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_TermLoanFacilityMember" xlink:label="loc_nx_TermLoanFacilityMember_89ABE36DB5ED9F72F10CABE17B206427" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:to="loc_nx_TermLoanFacilityMember_89ABE36DB5ED9F72F10CABE17B206427" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_619765389C08B0DDEC14ABE17B200791" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:to="loc_us-gaap_LineOfCreditMember_619765389C08B0DDEC14ABE17B200791" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_CapitalLeaseObligationsAndOtherMember" xlink:label="loc_nx_CapitalLeaseObligationsAndOtherMember_E705587A3695AFE33A9AABE17B20C0B6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:to="loc_nx_CapitalLeaseObligationsAndOtherMember_E705587A3695AFE33A9AABE17B20C0B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_EC95DA049A40B7618DE9ABE17B21EEB4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_EC95DA049A40B7618DE9ABE17B21EEB4" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_A2018CreditFacilityMember" xlink:label="loc_nx_A2018CreditFacilityMember_7F11DE0326DB7F5E59CBABE17B2180F3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_960531563802569D72C4ABE17B20F682" xlink:to="loc_nx_A2018CreditFacilityMember_7F11DE0326DB7F5E59CBABE17B2180F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_A02824D4101EFB20754DABE17B21EB2A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_A02824D4101EFB20754DABE17B21EB2A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_9367FD02C9C9DB96CF9DABE17B224640" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_9367FD02C9C9DB96CF9DABE17B224640" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_8759D82216B2833A4006ABE17B220FFD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_dei_DocumentPeriodEndDate_8759D82216B2833A4006ABE17B220FFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_769993A201FDDCAD733AABE17B227282" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_LineOfCredit_769993A201FDDCAD733AABE17B227282" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLongTermDebt" xlink:label="loc_us-gaap_OtherLongTermDebt_DFD4A5E30C8137588EC2ABE17B24EAC7" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_OtherLongTermDebt_DFD4A5E30C8137588EC2ABE17B24EAC7" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_Financeleaseobligationsandother" xlink:label="loc_nx_Financeleaseobligationsandother_D652CE3CAF32C544F1CCABE363629854" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_Financeleaseobligationsandother_D652CE3CAF32C544F1CCABE363629854" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredFinanceCostsOwnshareLendingArrangementIssuanceCostsNet" xlink:label="loc_us-gaap_DeferredFinanceCostsOwnshareLendingArrangementIssuanceCostsNet_10CD0DD8C01DDC7288A5ABE17B25199C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DeferredFinanceCostsOwnshareLendingArrangementIssuanceCostsNet_10CD0DD8C01DDC7288A5ABE17B25199C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_3BAB1B1B2077C74ABCF6ABE17B254E33" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_3BAB1B1B2077C74ABCF6ABE17B254E33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_680945FADC9ED45D2DC8ABE17B255799" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_680945FADC9ED45D2DC8ABE17B255799" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_481ABC2C1DEF6489449FABE17B25D8AE" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_481ABC2C1DEF6489449FABE17B25D8AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_AFF76CB6D3042B2053B1ABE17B2561F0" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_AFF76CB6D3042B2053B1ABE17B2561F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_FF6564E55654AFC528EFABE17B263865" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_FF6564E55654AFC528EFABE17B263865" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_LineofCreditFacilityMaximumBorrowingCapacityCommittedAmount" xlink:label="loc_nx_LineofCreditFacilityMaximumBorrowingCapacityCommittedAmount_AAF50B2107AF1BE44614ABE17B267FC3" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_LineofCreditFacilityMaximumBorrowingCapacityCommittedAmount_AAF50B2107AF1BE44614ABE17B267FC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_B38E3F051E2634013A42ABE17B26CA6E" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_B38E3F051E2634013A42ABE17B26CA6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_1590AFBC8A36A306B044ABE17B264D7A" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_1590AFBC8A36A306B044ABE17B264D7A" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_DebtInstrumentDebtDefaultInterestAccrualRate" xlink:label="loc_nx_DebtInstrumentDebtDefaultInterestAccrualRate_3CB39D13065C88FBADFCABE17B26CEA0" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_DebtInstrumentDebtDefaultInterestAccrualRate_3CB39D13065C88FBADFCABE17B26CEA0" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_DebtInstrumentRequiredLeverageRatio" xlink:label="loc_nx_DebtInstrumentRequiredLeverageRatio_8752932BD15A97D1F1E0ABE17B26BE03" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_DebtInstrumentRequiredLeverageRatio_8752932BD15A97D1F1E0ABE17B26BE03" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_DebtInstrumentLimitationonAnnualDividend" xlink:label="loc_nx_DebtInstrumentLimitationonAnnualDividend_B7F27CC618FBC319AA2DABE17B26CAE8" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_DebtInstrumentLimitationonAnnualDividend_B7F27CC618FBC319AA2DABE17B26CAE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_40FB46852946BB4F8560ABE17B272913" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_40FB46852946BB4F8560ABE17B272913" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_DebtInstrumentMaximumFixedChargeCoverageRatio" xlink:label="loc_nx_DebtInstrumentMaximumFixedChargeCoverageRatio_73D502C30F0C6025C528ABE17B27CC32" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_nx_DebtInstrumentMaximumFixedChargeCoverageRatio_73D502C30F0C6025C528ABE17B27CC32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_6AD639AD020D46928748ABE17B27714F" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_6AD639AD020D46928748ABE17B27714F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_04091EE93ABD56A43690ABE17B27A5BF" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_306017C3783ED04E23A8ABE17B21439E" xlink:to="loc_us-gaap_DebtDisclosureAbstract_04091EE93ABD56A43690ABE17B27A5BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_7E818F4521034578274CABE17B27CD1E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtDisclosureAbstract_04091EE93ABD56A43690ABE17B27A5BF" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_7E818F4521034578274CABE17B27CD1E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_E7A50C3BA573CB43878CABE17B279863" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtDisclosureAbstract_04091EE93ABD56A43690ABE17B27A5BF" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_E7A50C3BA573CB43878CABE17B279863" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DebtAndCapitalLeaseObligationsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DocumentAndEntityInformation" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_691AD29E74845F9F80A76D1CA8B3B765" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_63A698779C595DB48A536742B7FE0D2C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_691AD29E74845F9F80A76D1CA8B3B765" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_63A698779C595DB48A536742B7FE0D2C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_D6902E761DF856EFB10B558A7D307226" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_63A698779C595DB48A536742B7FE0D2C" xlink:to="loc_us-gaap_StatementClassOfStockAxis_D6902E761DF856EFB10B558A7D307226" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_AE0AB27EB513FF4C98AD914FF491B204_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_D6902E761DF856EFB10B558A7D307226" xlink:to="loc_us-gaap_ClassOfStockDomain_AE0AB27EB513FF4C98AD914FF491B204_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_989D1AFDE138593299F62BE61444E010" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_D6902E761DF856EFB10B558A7D307226" xlink:to="loc_us-gaap_ClassOfStockDomain_989D1AFDE138593299F62BE61444E010" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_806D91C31B125BDFA5A4C94E9AABE965" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_989D1AFDE138593299F62BE61444E010" xlink:to="loc_us-gaap_CommonStockMember_806D91C31B125BDFA5A4C94E9AABE965" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/EarningsPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/EarningsPerShareDetail" xlink:type="extended">
    <link:loc xlink:href="nx-20200131.xsd#nx_EarningsPerShareDisclosureLineItems" xlink:label="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:type="locator" />
    <link:loc xlink:href="nx-20200131.xsd#nx_EarningsPerShareDisclosureTable" xlink:label="loc_nx_EarningsPerShareDisclosureTable_EE0498CC9CC0285AC769548E9285B6A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_nx_EarningsPerShareDisclosureTable_EE0498CC9CC0285AC769548E9285B6A9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_511BB876A1B8A58BB383548E9285590C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_EarningsPerShareDisclosureTable_EE0498CC9CC0285AC769548E9285B6A9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_511BB876A1B8A58BB383548E9285590C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_511BB876A1B8A58BB383548E9285590C" xlink:to="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_511BB876A1B8A58BB383548E9285590C" xlink:to="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_F07BF034E4F42C9919B1548E928599C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:to="loc_us-gaap_CommonStockMember_F07BF034E4F42C9919B1548E928599C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_205D3FD83477653C1794548E92857F0C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:to="loc_us-gaap_EmployeeStockOptionMember_205D3FD83477653C1794548E92857F0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_4CB4E2562CF9E3BF1FA9548E92852917" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:to="loc_us-gaap_RestrictedStockMember_4CB4E2562CF9E3BF1FA9548E92852917" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_C1331DC2E9AE96B008AD548E92855D26" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:to="loc_us-gaap_PerformanceSharesMember_C1331DC2E9AE96B008AD548E92855D26" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_PerformanceRestrictedStockUnitsMember" xlink:label="loc_nx_PerformanceRestrictedStockUnitsMember_90BD2049A1B570CA10DB548E92852424" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_773712E5987FF9B9F1F3548E9285EEBD" xlink:to="loc_nx_PerformanceRestrictedStockUnitsMember_90BD2049A1B570CA10DB548E92852424" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_94D40B9785DFA347837B548E9285B9A2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_EarningsPerShareDisclosureTable_EE0498CC9CC0285AC769548E9285B6A9" xlink:to="loc_us-gaap_AwardTypeAxis_94D40B9785DFA347837B548E9285B9A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_94D40B9785DFA347837B548E9285B9A2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_94D40B9785DFA347837B548E9285B9A2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_C4271B55DFF5A08620AD548E928583E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964" xlink:to="loc_us-gaap_EmployeeStockOptionMember_C4271B55DFF5A08620AD548E928583E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_77728E80A8BEFB0D9FE1548E928530AB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964" xlink:to="loc_us-gaap_RestrictedStockMember_77728E80A8BEFB0D9FE1548E928530AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_7D9AD697D5CFADC43C67548E92855576" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_C0ADCA0FFF7A59744F99548E92852964" xlink:to="loc_us-gaap_PerformanceSharesMember_7D9AD697D5CFADC43C67548E92855576" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_98171AB413ACB7E14318548E9285EF38" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_98171AB413ACB7E14318548E9285EF38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_0437DD17879EEA5BBB66548E92954B23" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_0437DD17879EEA5BBB66548E92954B23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_727814F7C387338C1B12548E9295E6F5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_727814F7C387338C1B12548E9295E6F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_3742331304F5962FA981548E92954846" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_3742331304F5962FA981548E92954846" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_9140659EEE02D192F851548E929594A2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_9140659EEE02D192F851548E929594A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_9D0F0443126BD53AE971548E9295AE2D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_9D0F0443126BD53AE971548E9295AE2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_390AB1B6C931773156A3548E92955C4F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_390AB1B6C931773156A3548E92955C4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDiluted_D997566EC9D874BD939D548E9295DCD1" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDiluted_D997566EC9D874BD939D548E9295DCD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_CBBE68D92176A2FC163B548E92959FB3" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_CBBE68D92176A2FC163B548E92959FB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_5CFC03C5963FE598C3CF548E9295A879" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_9ED8CADB6D3631337B43548E92853A95" xlink:to="loc_us-gaap_EarningsPerShareDiluted_5CFC03C5963FE598C3CF548E9295A879" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/EarningsPerShareEarningsPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/FairValueMeasurementOfAssetsAndLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/FairValueMeasurementOfAssetsAndLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2F7BFD1C147A5659AB4A1A1348C16B58" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D4755FE2AA5B56FCA74E572729C1D091" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2F7BFD1C147A5659AB4A1A1348C16B58" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D4755FE2AA5B56FCA74E572729C1D091" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4B2AEE5022F754BC8AE7673148032CAB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D4755FE2AA5B56FCA74E572729C1D091" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4B2AEE5022F754BC8AE7673148032CAB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBAB5065C055022DED00FCBFED6F7580_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4B2AEE5022F754BC8AE7673148032CAB" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_BBAB5065C055022DED00FCBFED6F7580_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6C0F74F7A422548B9C05F436EF54F7B1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4B2AEE5022F754BC8AE7673148032CAB" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6C0F74F7A422548B9C05F436EF54F7B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_A3EBFCBE2B895A5E886F16F4436207C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6C0F74F7A422548B9C05F436EF54F7B1" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_A3EBFCBE2B895A5E886F16F4436207C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue" xlink:label="loc_us-gaap_ForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_CF635AE7016D59778935891887201A90" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2F7BFD1C147A5659AB4A1A1348C16B58" xlink:to="loc_us-gaap_ForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_CF635AE7016D59778935891887201A90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_94FC6EA28CF15CC7A03175A5CCE487CB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_2F7BFD1C147A5659AB4A1A1348C16B58" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_94FC6EA28CF15CC7A03175A5CCE487CB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/FairValueMeasurementOfAssetsAndLiabilitiesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssetsGoodwillDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_F9DA8077861E5C15CD2B1F9F97085136" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_C44A5809775F5D9D19021F9F97018FFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_F9DA8077861E5C15CD2B1F9F97085136" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_C44A5809775F5D9D19021F9F97018FFF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7507E98F7A72914CB8541F9F9701BCF5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_C44A5809775F5D9D19021F9F97018FFF" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7507E98F7A72914CB8541F9F9701BCF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8A49109327094EB256081F9F9702C899_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7507E98F7A72914CB8541F9F9701BCF5" xlink:to="loc_us-gaap_SegmentDomain_8A49109327094EB256081F9F9702C899_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8A49109327094EB256081F9F9702C899" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7507E98F7A72914CB8541F9F9701BCF5" xlink:to="loc_us-gaap_SegmentDomain_8A49109327094EB256081F9F9702C899" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NACabinetComponentsMember" xlink:label="loc_nx_NACabinetComponentsMember_2EA8DAD2CA07759BA9781F9F9702833D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8A49109327094EB256081F9F9702C899" xlink:to="loc_nx_NACabinetComponentsMember_2EA8DAD2CA07759BA9781F9F9702833D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_94F570921E68B16A41DC1F9F97083898" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_F9DA8077861E5C15CD2B1F9F97085136" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_94F570921E68B16A41DC1F9F97083898" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_CD457F7EAE75E8417DF81F9F97089517" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_F9DA8077861E5C15CD2B1F9F97085136" xlink:to="loc_us-gaap_GoodwillRollForward_CD457F7EAE75E8417DF81F9F97089517" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_D64FFF15FD8C8EF122441F9F97087C49" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_CD457F7EAE75E8417DF81F9F97089517" xlink:to="loc_us-gaap_Goodwill_D64FFF15FD8C8EF122441F9F97087C49" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_008F46A91ECAE6EBA79D1F9F97091634" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_CD457F7EAE75E8417DF81F9F97089517" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_008F46A91ECAE6EBA79D1F9F97091634" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssetsIdentifiableIntangibleAssetsDetail" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_460B1D8A63A92EAF61C85F3F91793833" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1B96D5BF34214176F9AB5F3F917898E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_460B1D8A63A92EAF61C85F3F91793833" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1B96D5BF34214176F9AB5F3F917898E1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_CCB7BE29E891A4D051F15F3F91788E76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_1B96D5BF34214176F9AB5F3F917898E1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_CCB7BE29E891A4D051F15F3F91788E76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_CCB7BE29E891A4D051F15F3F91788E76" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_CCB7BE29E891A4D051F15F3F91788E76" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_3694F2153B4BAE31C0505F3F9179E2EC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747" xlink:to="loc_us-gaap_CustomerRelationshipsMember_3694F2153B4BAE31C0505F3F9179E2EC" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_TradenamesAndTrademarksMember" xlink:label="loc_nx_TradenamesAndTrademarksMember_F983D70C8AC243AA14635F3F9179C9F7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747" xlink:to="loc_nx_TradenamesAndTrademarksMember_F983D70C8AC243AA14635F3F9179C9F7" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_PatentsAndOtherTechnologyMember" xlink:label="loc_nx_PatentsAndOtherTechnologyMember_6FE3A1DE77BE400B073F5F3F91797345" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_D69BA2031A85585D1CF45F3F91796747" xlink:to="loc_nx_PatentsAndOtherTechnologyMember_6FE3A1DE77BE400B073F5F3F91797345" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_E74606AEFE6910D2CD1B5F3F917A5E47" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_460B1D8A63A92EAF61C85F3F91793833" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_E74606AEFE6910D2CD1B5F3F917A5E47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_802C2EEDB59CF8D7AADB5F3F917A01E7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_460B1D8A63A92EAF61C85F3F91793833" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_802C2EEDB59CF8D7AADB5F3F917A01E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_1E0981E3E7A0E0BC674C5F3F917A4E96" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_460B1D8A63A92EAF61C85F3F91793833" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_1E0981E3E7A0E0BC674C5F3F917A4E96" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillAndIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/IncomeTaxesDetail" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExaminationLineItems" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxExaminationTable" xlink:label="loc_us-gaap_IncomeTaxExaminationTable_4F526C4A29B27418FA565F3F90C40063" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_us-gaap_IncomeTaxExaminationTable_4F526C4A29B27418FA565F3F90C40063" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityByLocationAxis" xlink:label="loc_dei_EntityByLocationAxis_4ADF8844957B9A7AB7A25F3F90C4383D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_4F526C4A29B27418FA565F3F90C40063" xlink:to="loc_dei_EntityByLocationAxis_4ADF8844957B9A7AB7A25F3F90C4383D" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LocationDomain" xlink:label="loc_dei_LocationDomain_9C361E24F1EB98F346815F3F90C4D718_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_EntityByLocationAxis_4ADF8844957B9A7AB7A25F3F90C4383D" xlink:to="loc_dei_LocationDomain_9C361E24F1EB98F346815F3F90C4D718_default" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LocationDomain" xlink:label="loc_dei_LocationDomain_9C361E24F1EB98F346815F3F90C4D718" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_EntityByLocationAxis_4ADF8844957B9A7AB7A25F3F90C4383D" xlink:to="loc_dei_LocationDomain_9C361E24F1EB98F346815F3F90C4D718" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementEarlyAdoptionAxis" xlink:label="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_9893994EC795D1F94A375F3F90C5B6B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_4F526C4A29B27418FA565F3F90C40063" xlink:to="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_9893994EC795D1F94A375F3F90C5B6B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_9D5AA903CFF9A76F0AC35F3F90C58F56_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_9893994EC795D1F94A375F3F90C5B6B5" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_9D5AA903CFF9A76F0AC35F3F90C58F56_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPrinciplesEarlyAdoptionMember" xlink:label="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_9D5AA903CFF9A76F0AC35F3F90C58F56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NewAccountingPronouncementEarlyAdoptionAxis_9893994EC795D1F94A375F3F90C5B6B5" xlink:to="loc_us-gaap_NewAccountingPrinciplesEarlyAdoptionMember_9D5AA903CFF9A76F0AC35F3F90C58F56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_233B9FEC0C9CD163E6395F3F90C50918" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_4F526C4A29B27418FA565F3F90C40063" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_233B9FEC0C9CD163E6395F3F90C50918" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_50045A922C9AA492FFFA5F3F90C55AF2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_233B9FEC0C9CD163E6395F3F90C50918" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_50045A922C9AA492FFFA5F3F90C55AF2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_50045A922C9AA492FFFA5F3F90C55AF2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_233B9FEC0C9CD163E6395F3F90C50918" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_50045A922C9AA492FFFA5F3F90C55AF2" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_7DD52A175235AEAA1F605F3F90C60B18" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_4F526C4A29B27418FA565F3F90C40063" xlink:to="loc_dei_LegalEntityAxis_7DD52A175235AEAA1F605F3F90C60B18" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_3C895A1888C81D97EDC75F3F90C6D4AC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_7DD52A175235AEAA1F605F3F90C60B18" xlink:to="loc_dei_EntityDomain_3C895A1888C81D97EDC75F3F90C6D4AC_default" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_3C895A1888C81D97EDC75F3F90C6D4AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_7DD52A175235AEAA1F605F3F90C60B18" xlink:to="loc_dei_EntityDomain_3C895A1888C81D97EDC75F3F90C6D4AC" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_BEF0BC7C673705B213AC5F3F90CC09AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_dei_DocumentPeriodEndDate_BEF0BC7C673705B213AC5F3F90CC09AF" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ExpectedEffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_nx_ExpectedEffectiveIncomeTaxRateContinuingOperations_EF491F3C51CE1337F1B35F3F90CC054A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_nx_ExpectedEffectiveIncomeTaxRateContinuingOperations_EF491F3C51CE1337F1B35F3F90CC054A" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_TaxCutsandJobsActof2017TransitionTaxforAccumulatedForeignEarningsIncomeTaxExpenseBenefit" xlink:label="loc_nx_TaxCutsandJobsActof2017TransitionTaxforAccumulatedForeignEarningsIncomeTaxExpenseBenefit_C0A50E63A4B1552422405F3F90CC2DB8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_nx_TaxCutsandJobsActof2017TransitionTaxforAccumulatedForeignEarningsIncomeTaxExpenseBenefit_C0A50E63A4B1552422405F3F90CC2DB8" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_TaxCutsandJobsActof2017ExcessTaxBenefits" xlink:label="loc_nx_TaxCutsandJobsActof2017ExcessTaxBenefits_28BB0747F041EC8D69D05F3F90CC51E5" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_nx_TaxCutsandJobsActof2017ExcessTaxBenefits_28BB0747F041EC8D69D05F3F90CC51E5" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_TaxCutsandJobsActof2017GILTIandFDII" xlink:label="loc_nx_TaxCutsandJobsActof2017GILTIandFDII_07D0D6712B761F4DB2925F3F90CD6B8F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_nx_TaxCutsandJobsActof2017GILTIandFDII_07D0D6712B761F4DB2925F3F90CD6B8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_808F4B58890B75C134455F3F90CED9CC" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_808F4B58890B75C134455F3F90CED9CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_310F9638547996841BC15F3F90CF1E4D" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_F790A32DD7D000C842125F3F90C63B34" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_310F9638547996841BC15F3F90CF1E4D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/IncomeTaxesIncomeTaxTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/Inventories" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/InventoriesDetail" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_2CE24E85E91A04E116C55F3F91AAF707" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_60639E39C8020D9E3F2D5F3F91A879BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2CE24E85E91A04E116C55F3F91AAF707" xlink:to="loc_us-gaap_StatementTable_60639E39C8020D9E3F2D5F3F91A879BC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_0F6798B802B21D147F475F3F91A989D5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_60639E39C8020D9E3F2D5F3F91A879BC" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_0F6798B802B21D147F475F3F91A989D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_3F9297E57BF7CD20E8EF5F3F91A9CE73_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_0F6798B802B21D147F475F3F91A989D5" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_3F9297E57BF7CD20E8EF5F3F91A9CE73_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_3F9297E57BF7CD20E8EF5F3F91A9CE73" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_0F6798B802B21D147F475F3F91A989D5" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_3F9297E57BF7CD20E8EF5F3F91A9CE73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_32BD24D95289B2E772EE5F3F91AA819E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2CE24E85E91A04E116C55F3F91AAF707" xlink:to="loc_us-gaap_InventoryNet_32BD24D95289B2E772EE5F3F91AA819E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_7AB18ABD4233317182A85F3F91AA2D54" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2CE24E85E91A04E116C55F3F91AAF707" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_7AB18ABD4233317182A85F3F91AA2D54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_69634C1762EFAC544FC85F3F91AB10DD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2CE24E85E91A04E116C55F3F91AAF707" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_69634C1762EFAC544FC85F3F91AB10DD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/InventoriesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/Leases" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_94C342B9331A5929BAD57E7E6C71A265" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_37A5BAFB86E19127B1CC7E7E6C71143D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_94C342B9331A5929BAD57E7E6C71A265" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_37A5BAFB86E19127B1CC7E7E6C71143D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2AEF956BDBBD866E812C7E7F25B634A6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_37A5BAFB86E19127B1CC7E7E6C71143D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2AEF956BDBBD866E812C7E7F25B634A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5CDC9CD2A3CD9226E49D7E7F7AC2C498_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2AEF956BDBBD866E812C7E7F25B634A6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5CDC9CD2A3CD9226E49D7E7F7AC2C498_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5CDC9CD2A3CD9226E49D7E7F7AC2C498" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2AEF956BDBBD866E812C7E7F25B634A6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5CDC9CD2A3CD9226E49D7E7F7AC2C498" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_BuildingMember" xlink:label="loc_us-gaap_BuildingMember_FF4A58F6DF074CF22D727E87022748CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5CDC9CD2A3CD9226E49D7E7F7AC2C498" xlink:to="loc_us-gaap_BuildingMember_FF4A58F6DF074CF22D727E87022748CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EquipmentMember" xlink:label="loc_us-gaap_EquipmentMember_DCC47A50836ABAD737D97E8686A2F4E5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5CDC9CD2A3CD9226E49D7E7F7AC2C498" xlink:to="loc_us-gaap_EquipmentMember_DCC47A50836ABAD737D97E8686A2F4E5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_69DE90F73C04807BD2C77E801DAE494D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_37A5BAFB86E19127B1CC7E7E6C71143D" xlink:to="loc_srt_RangeAxis_69DE90F73C04807BD2C77E801DAE494D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_CBB4F8CA4F04BBE4029D7E801F25D66D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_69DE90F73C04807BD2C77E801DAE494D" xlink:to="loc_srt_RangeMember_CBB4F8CA4F04BBE4029D7E801F25D66D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_CBB4F8CA4F04BBE4029D7E801F25D66D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_69DE90F73C04807BD2C77E801DAE494D" xlink:to="loc_srt_RangeMember_CBB4F8CA4F04BBE4029D7E801F25D66D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_1B6E87A0447F7423811E7E805D69FEF6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_CBB4F8CA4F04BBE4029D7E801F25D66D" xlink:to="loc_srt_MinimumMember_1B6E87A0447F7423811E7E805D69FEF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_80C6AC19BBF59B7D5B077E808D59D0F3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_CBB4F8CA4F04BBE4029D7E801F25D66D" xlink:to="loc_srt_MaximumMember_80C6AC19BBF59B7D5B077E808D59D0F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_2904E889EB36FAB4B7B97E7E8F3D1739" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_94C342B9331A5929BAD57E7E6C71A265" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_2904E889EB36FAB4B7B97E7E8F3D1739" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesFutureMinimumLeasePaymentsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesLeaseCostsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesLeaseRelatedAssetsAndLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesPresentMaturityOfLeaseLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesSupplementalCashFlowInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/LeasesWeightedAverageRemainingLeaseTermsAndWeightedAverageDiscountRatesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_15DF4A0B6A91568CE2415E8A988BC337" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_068AE65D91E543267EC45E8A987B0324" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_15DF4A0B6A91568CE2415E8A988BC337" xlink:to="loc_us-gaap_StatementTable_068AE65D91E543267EC45E8A987B0324" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_F8929EED4F6144A4FB685E8A988BA9DA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_068AE65D91E543267EC45E8A987B0324" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_F8929EED4F6144A4FB685E8A988BA9DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8D4123F6218BA4D6F5005E8A988BE052_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F8929EED4F6144A4FB685E8A988BA9DA" xlink:to="loc_us-gaap_SegmentDomain_8D4123F6218BA4D6F5005E8A988BE052_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8D4123F6218BA4D6F5005E8A988BE052" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F8929EED4F6144A4FB685E8A988BA9DA" xlink:to="loc_us-gaap_SegmentDomain_8D4123F6218BA4D6F5005E8A988BE052" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NAFenestrationMember" xlink:label="loc_nx_NAFenestrationMember_EF0AC7C0DD36AB5F13095E8A988BCC03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8D4123F6218BA4D6F5005E8A988BE052" xlink:to="loc_nx_NAFenestrationMember_EF0AC7C0DD36AB5F13095E8A988BCC03" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NACabinetComponentsMember" xlink:label="loc_nx_NACabinetComponentsMember_1C517D4833336ACBC0D75E8A988BD3C8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8D4123F6218BA4D6F5005E8A988BE052" xlink:to="loc_nx_NACabinetComponentsMember_1C517D4833336ACBC0D75E8A988BD3C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_CFABFE51302E90BCA2BF5E8A988B47BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_15DF4A0B6A91568CE2415E8A988BC337" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_CFABFE51302E90BCA2BF5E8A988B47BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestructuringCosts" xlink:label="loc_us-gaap_RestructuringCosts_94E83F3D522F3887B9225E8A988BC88E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_15DF4A0B6A91568CE2415E8A988BC337" xlink:to="loc_us-gaap_RestructuringCosts_94E83F3D522F3887B9225E8A988BC88E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentationSummaryOfProductSalesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProductInformationLineItems" xlink:label="loc_us-gaap_ProductInformationLineItems_50667DFD6075528799A2216DE30D93C6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfProductInformationTable" xlink:label="loc_us-gaap_ScheduleOfProductInformationTable_E01B9837F0945A8FA3B284DFC9A9DCDA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductInformationLineItems_50667DFD6075528799A2216DE30D93C6" xlink:to="loc_us-gaap_ScheduleOfProductInformationTable_E01B9837F0945A8FA3B284DFC9A9DCDA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_D49F9B0D90E256699DB45DCF59C6EAF7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_E01B9837F0945A8FA3B284DFC9A9DCDA" xlink:to="loc_srt_ConsolidationItemsAxis_D49F9B0D90E256699DB45DCF59C6EAF7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_97853A363A7329857B09FC69E7983F67_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_D49F9B0D90E256699DB45DCF59C6EAF7" xlink:to="loc_srt_ConsolidationItemsDomain_97853A363A7329857B09FC69E7983F67_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_9940679EAE2E56788B75463C3421EA32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_D49F9B0D90E256699DB45DCF59C6EAF7" xlink:to="loc_srt_ConsolidationItemsDomain_9940679EAE2E56788B75463C3421EA32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_CE31873C77EE5329A772660FC78C011A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9940679EAE2E56788B75463C3421EA32" xlink:to="loc_us-gaap_OperatingSegmentsMember_CE31873C77EE5329A772660FC78C011A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_74F1BD65402D56AD8C5FAFA017476F0D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9940679EAE2E56788B75463C3421EA32" xlink:to="loc_us-gaap_CorporateNonSegmentMember_74F1BD65402D56AD8C5FAFA017476F0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_B6C180392447521D8AA9CEDDB22EFB70" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_E01B9837F0945A8FA3B284DFC9A9DCDA" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_B6C180392447521D8AA9CEDDB22EFB70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_9072BDBAD1E16EEB824DFC69E799FF38_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B6C180392447521D8AA9CEDDB22EFB70" xlink:to="loc_us-gaap_SegmentDomain_9072BDBAD1E16EEB824DFC69E799FF38_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_A7D92250BE7858D886A95BC42C85898B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B6C180392447521D8AA9CEDDB22EFB70" xlink:to="loc_us-gaap_SegmentDomain_A7D92250BE7858D886A95BC42C85898B" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NAEngineeredComponentsMember" xlink:label="loc_nx_NAEngineeredComponentsMember_A88DDE6DD6815C61B0C48978DBC63087" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_A7D92250BE7858D886A95BC42C85898B" xlink:to="loc_nx_NAEngineeredComponentsMember_A88DDE6DD6815C61B0C48978DBC63087" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_EUEngineeredComponentsMember" xlink:label="loc_nx_EUEngineeredComponentsMember_4C41095CF028508894F451F8B7BF429F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_A7D92250BE7858D886A95BC42C85898B" xlink:to="loc_nx_EUEngineeredComponentsMember_4C41095CF028508894F451F8B7BF429F" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NACabinetComponentsMember" xlink:label="loc_nx_NACabinetComponentsMember_77ADC72F56435012B1A3DE8EC01E5D1D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_A7D92250BE7858D886A95BC42C85898B" xlink:to="loc_nx_NACabinetComponentsMember_77ADC72F56435012B1A3DE8EC01E5D1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_AC34C602E002515CB7908B78ED6E16C6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_E01B9837F0945A8FA3B284DFC9A9DCDA" xlink:to="loc_srt_StatementGeographicalAxis_AC34C602E002515CB7908B78ED6E16C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_1F9B5ABC2E3F2B9CDEE4FC69E79A9BED_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_AC34C602E002515CB7908B78ED6E16C6" xlink:to="loc_srt_SegmentGeographicalDomain_1F9B5ABC2E3F2B9CDEE4FC69E79A9BED_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_E3584D1482FB5EFDB6155BEBA9C0EB1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_AC34C602E002515CB7908B78ED6E16C6" xlink:to="loc_srt_SegmentGeographicalDomain_E3584D1482FB5EFDB6155BEBA9C0EB1B" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_InternationalMember" xlink:label="loc_nx_InternationalMember_C738B7124C15537488CCC961C7BF8C5F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_E3584D1482FB5EFDB6155BEBA9C0EB1B" xlink:to="loc_nx_InternationalMember_C738B7124C15537488CCC961C7BF8C5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_D7B8B11374BD536687AB89760116644D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_E3584D1482FB5EFDB6155BEBA9C0EB1B" xlink:to="loc_country_US_D7B8B11374BD536687AB89760116644D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_38A05957CA9750CCB884092E832EADD4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_E01B9837F0945A8FA3B284DFC9A9DCDA" xlink:to="loc_srt_ProductOrServiceAxis_38A05957CA9750CCB884092E832EADD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_4B32692ACE7A6D966633FC69E79B3A11_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_38A05957CA9750CCB884092E832EADD4" xlink:to="loc_srt_ProductsAndServicesDomain_4B32692ACE7A6D966633FC69E79B3A11_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_7435ACDA75EE5D389667234859F8620D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_38A05957CA9750CCB884092E832EADD4" xlink:to="loc_srt_ProductsAndServicesDomain_7435ACDA75EE5D389667234859F8620D" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NonfenestrationMember" xlink:label="loc_nx_NonfenestrationMember_9B946A0CAD405BB1802F18A7F6F77848" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7435ACDA75EE5D389667234859F8620D" xlink:to="loc_nx_NonfenestrationMember_9B946A0CAD405BB1802F18A7F6F77848" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_FenestrationMember" xlink:label="loc_nx_FenestrationMember_1D2C6E0A23835214BDD98162FFC08394" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7435ACDA75EE5D389667234859F8620D" xlink:to="loc_nx_FenestrationMember_1D2C6E0A23835214BDD98162FFC08394" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_DDD194EDCA1750F091AA33FE714F0174" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_50667DFD6075528799A2216DE30D93C6" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_DDD194EDCA1750F091AA33FE714F0174" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureOfOperationsAndBasisOfPresentationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NewAccountingGuidanceAdopted" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NewAccountingGuidanceAdoptedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_5707E215F596D6FC064F7E87768654F6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_AA8CA374C2E4E3CC01147E877677C9A5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_5707E215F596D6FC064F7E87768654F6" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_AA8CA374C2E4E3CC01147E877677C9A5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis" xlink:label="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_AD65CA4DFEEF5C1176CE7E8776773E69" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_AA8CA374C2E4E3CC01147E877677C9A5" xlink:to="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_AD65CA4DFEEF5C1176CE7E8776773E69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_8284F7C0CF3766CA22FF7E87767775C8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_AD65CA4DFEEF5C1176CE7E8776773E69" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_8284F7C0CF3766CA22FF7E87767775C8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ChangeInAccountingPrincipleMember" xlink:label="loc_us-gaap_ChangeInAccountingPrincipleMember_8284F7C0CF3766CA22FF7E87767775C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis_AD65CA4DFEEF5C1176CE7E8776773E69" xlink:to="loc_us-gaap_ChangeInAccountingPrincipleMember_8284F7C0CF3766CA22FF7E87767775C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_3C5ADFC57B0F092800417E877677782E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingPrincipleMember_8284F7C0CF3766CA22FF7E87767775C8" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_3C5ADFC57B0F092800417E877677782E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_1179A8A37295C5F3584A7E87768663B3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_5707E215F596D6FC064F7E87768654F6" xlink:to="loc_us-gaap_OperatingLeaseLiability_1179A8A37295C5F3584A7E87768663B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_9B0DEF88AE7FE5F2C82F7E877686E8B6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_5707E215F596D6FC064F7E87768654F6" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_9B0DEF88AE7FE5F2C82F7E877686E8B6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/OtherIncomeExpense" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseDetail" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/RetirementPlans" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/RetirementPlansDetail" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/RetirementPlansTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_4BE8903C65F8539BAC5DFC9EBF85732E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_040A04D7C92E587FB99DEA7B345293CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4BE8903C65F8539BAC5DFC9EBF85732E" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_040A04D7C92E587FB99DEA7B345293CD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_20C533BDFAB154288B2636356AF57EBB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_040A04D7C92E587FB99DEA7B345293CD" xlink:to="loc_srt_ConsolidationItemsAxis_20C533BDFAB154288B2636356AF57EBB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_A3E6405F93EA4E6BA3EEFC69E7838740_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_20C533BDFAB154288B2636356AF57EBB" xlink:to="loc_srt_ConsolidationItemsDomain_A3E6405F93EA4E6BA3EEFC69E7838740_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_682F0B9FF3305725B8B20F832E53F9A5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_20C533BDFAB154288B2636356AF57EBB" xlink:to="loc_srt_ConsolidationItemsDomain_682F0B9FF3305725B8B20F832E53F9A5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_36EF8EF74D055FCBB9F4BD231773254D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_682F0B9FF3305725B8B20F832E53F9A5" xlink:to="loc_us-gaap_OperatingSegmentsMember_36EF8EF74D055FCBB9F4BD231773254D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_ED0349A620E0559B8CC97C54537447B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_682F0B9FF3305725B8B20F832E53F9A5" xlink:to="loc_us-gaap_CorporateNonSegmentMember_ED0349A620E0559B8CC97C54537447B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_AA0E297383395BA7BB760F17836135C8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_040A04D7C92E587FB99DEA7B345293CD" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_AA0E297383395BA7BB760F17836135C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_D28C28AAD8CDE9C5BFD6FC69E7848E9E_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AA0E297383395BA7BB760F17836135C8" xlink:to="loc_us-gaap_SegmentDomain_D28C28AAD8CDE9C5BFD6FC69E7848E9E_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_8BDABA5C01DC5B6CAA1C62397ED911C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AA0E297383395BA7BB760F17836135C8" xlink:to="loc_us-gaap_SegmentDomain_8BDABA5C01DC5B6CAA1C62397ED911C2" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NAEngineeredComponentsMember" xlink:label="loc_nx_NAEngineeredComponentsMember_03C6D7B88010597FAC96F73F9AF9EB53" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8BDABA5C01DC5B6CAA1C62397ED911C2" xlink:to="loc_nx_NAEngineeredComponentsMember_03C6D7B88010597FAC96F73F9AF9EB53" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_EUEngineeredComponentsMember" xlink:label="loc_nx_EUEngineeredComponentsMember_E1079CB59373557C8E0B4A93C7C6AD70" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8BDABA5C01DC5B6CAA1C62397ED911C2" xlink:to="loc_nx_EUEngineeredComponentsMember_E1079CB59373557C8E0B4A93C7C6AD70" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NACabinetComponentsMember" xlink:label="loc_nx_NACabinetComponentsMember_B71B0DD24EF65C42852EADF2B446B53E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8BDABA5C01DC5B6CAA1C62397ED911C2" xlink:to="loc_nx_NACabinetComponentsMember_B71B0DD24EF65C42852EADF2B446B53E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_E7C7AA478A0C50B5B49C66C18D4717EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4BE8903C65F8539BAC5DFC9EBF85732E" xlink:to="loc_us-gaap_NumberOfReportableSegments_E7C7AA478A0C50B5B49C66C18D4717EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NumberOfOperatingSegments" xlink:label="loc_us-gaap_NumberOfOperatingSegments_EDBC907BB6CF51B0844FC4B0862B0459" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4BE8903C65F8539BAC5DFC9EBF85732E" xlink:to="loc_us-gaap_NumberOfOperatingSegments_EDBC907BB6CF51B0844FC4B0862B0459" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_3D5E5E88AA595B498EEE5453F1FF8FE5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4BE8903C65F8539BAC5DFC9EBF85732E" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_3D5E5E88AA595B498EEE5453F1FF8FE5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationGoodwillBySegmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_1DFE6B811193B8AF394D5F3F8F6BB4D6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_21DCDAFCEA44FC1DBD665F3F8F685AE7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_1DFE6B811193B8AF394D5F3F8F6BB4D6" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_21DCDAFCEA44FC1DBD665F3F8F685AE7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_DE2CA9FC9F385BEC9C8B5F3F8F694507" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_21DCDAFCEA44FC1DBD665F3F8F685AE7" xlink:to="loc_srt_ConsolidationItemsAxis_DE2CA9FC9F385BEC9C8B5F3F8F694507" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_920F0EB216C0372CEC085F3F8F69DF84_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_DE2CA9FC9F385BEC9C8B5F3F8F694507" xlink:to="loc_srt_ConsolidationItemsDomain_920F0EB216C0372CEC085F3F8F69DF84_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_920F0EB216C0372CEC085F3F8F69DF84" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_DE2CA9FC9F385BEC9C8B5F3F8F694507" xlink:to="loc_srt_ConsolidationItemsDomain_920F0EB216C0372CEC085F3F8F69DF84" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_67A04DC763516F4364995F3F8F699847" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_920F0EB216C0372CEC085F3F8F69DF84" xlink:to="loc_us-gaap_OperatingSegmentsMember_67A04DC763516F4364995F3F8F699847" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_7A87A2E2E47896C0ADE85F3F8F6973F0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_920F0EB216C0372CEC085F3F8F69DF84" xlink:to="loc_us-gaap_CorporateNonSegmentMember_7A87A2E2E47896C0ADE85F3F8F6973F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_B5E8A3B4606816AA05CE5F3F8F6AF9B2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_21DCDAFCEA44FC1DBD665F3F8F685AE7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_B5E8A3B4606816AA05CE5F3F8F6AF9B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B5E8A3B4606816AA05CE5F3F8F6AF9B2" xlink:to="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B5E8A3B4606816AA05CE5F3F8F6AF9B2" xlink:to="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NAEngineeredComponentsMember" xlink:label="loc_nx_NAEngineeredComponentsMember_AD59F15E4D110BAC96285F3F8F6A3726" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F" xlink:to="loc_nx_NAEngineeredComponentsMember_AD59F15E4D110BAC96285F3F8F6A3726" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_EUEngineeredComponentsMember" xlink:label="loc_nx_EUEngineeredComponentsMember_8066385EFFFEDEBB197E5F3F8F6A9B56" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F" xlink:to="loc_nx_EUEngineeredComponentsMember_8066385EFFFEDEBB197E5F3F8F6A9B56" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NACabinetComponentsMember" xlink:label="loc_nx_NACabinetComponentsMember_EDE03695E1011F7BB8EC5F3F8F6AB92D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9C7055A6E19E0F368FBC5F3F8F6A643F" xlink:to="loc_nx_NACabinetComponentsMember_EDE03695E1011F7BB8EC5F3F8F6AB92D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_CE768823ADDE74E9B91E5F3F8F6BA736" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_1DFE6B811193B8AF394D5F3F8F6BB4D6" xlink:to="loc_us-gaap_Goodwill_CE768823ADDE74E9B91E5F3F8F6BA736" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_0DDA5BFC9205D08857C85F3F8F6BCB44" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_1DFE6B811193B8AF394D5F3F8F6BB4D6" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_0DDA5BFC9205D08857C85F3F8F6BCB44" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationReconcilliationOfOperatingLossToNetIncomeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationSegmentReportingInformationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C0A015F8C2605058113E5E8A97196919" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C0A015F8C2605058113E5E8A97196919" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_9A7AF53EB632451C0DBE5E8A97194261" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C0A015F8C2605058113E5E8A97196919" xlink:to="loc_srt_ConsolidationItemsAxis_9A7AF53EB632451C0DBE5E8A97194261" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_AB79D96DC77174A4255E5E8A9719C132_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_9A7AF53EB632451C0DBE5E8A97194261" xlink:to="loc_srt_ConsolidationItemsDomain_AB79D96DC77174A4255E5E8A9719C132_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_AB79D96DC77174A4255E5E8A9719C132" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_9A7AF53EB632451C0DBE5E8A97194261" xlink:to="loc_srt_ConsolidationItemsDomain_AB79D96DC77174A4255E5E8A9719C132" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_3F8A75A8999C2EA864A25E8A97197CB7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_AB79D96DC77174A4255E5E8A9719C132" xlink:to="loc_us-gaap_OperatingSegmentsMember_3F8A75A8999C2EA864A25E8A97197CB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_B0EBC4A95BCBD612213C5E8A97198EEE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_AB79D96DC77174A4255E5E8A9719C132" xlink:to="loc_us-gaap_CorporateNonSegmentMember_B0EBC4A95BCBD612213C5E8A97198EEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8824C80B7DDA43A353BD5E8A9719771D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_C0A015F8C2605058113E5E8A97196919" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8824C80B7DDA43A353BD5E8A9719771D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8824C80B7DDA43A353BD5E8A9719771D" xlink:to="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8824C80B7DDA43A353BD5E8A9719771D" xlink:to="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NAFenestrationMember" xlink:label="loc_nx_NAFenestrationMember_A2ADF5D22E79942949935E8A9719EA7E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F" xlink:to="loc_nx_NAFenestrationMember_A2ADF5D22E79942949935E8A9719EA7E" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_EUFenestrationMember" xlink:label="loc_nx_EUFenestrationMember_30DDD242716C6D7CD3AF5E8A9719B7FD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F" xlink:to="loc_nx_EUFenestrationMember_30DDD242716C6D7CD3AF5E8A9719B7FD" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_NACabinetComponentsMember" xlink:label="loc_nx_NACabinetComponentsMember_ECACCF5B09ED18B8C60D5E8A97194604" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_D204BCF628EDAC1241D45E8A9719279F" xlink:to="loc_nx_NACabinetComponentsMember_ECACCF5B09ED18B8C60D5E8A97194604" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_23F9C160C11BE5A31D455E8A97191A1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_23F9C160C11BE5A31D455E8A97191A1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_1A0400F55804D6C67C015E8A971923B2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_1A0400F55804D6C67C015E8A971923B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_3F1619EB26680187F1AD5E8A97194C69" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_3F1619EB26680187F1AD5E8A97194C69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_6EDD717A3F8BE5C9F1A45E8A97195E46" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_OperatingIncomeLoss_6EDD717A3F8BE5C9F1A45E8A97195E46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_4B3758BE822A019AF3FF5E8A97193B3B" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_4B3758BE822A019AF3FF5E8A97193B3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_D36097B2D265E58795ED5E8A971980A7" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_E32746F67096B55EAE2E5E8A97198916" xlink:to="loc_us-gaap_Assets_D36097B2D265E58795ED5E8A971980A7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationDetail" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_682517944B6D56BD82FD6DBF7F406A63" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_FCAA350F670E5983B0361C2D34AB7053" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_682517944B6D56BD82FD6DBF7F406A63" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_FCAA350F670E5983B0361C2D34AB7053" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_C24AD438216256CEBB0F5B646E5C4182" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_FCAA350F670E5983B0361C2D34AB7053" xlink:to="loc_us-gaap_AwardTypeAxis_C24AD438216256CEBB0F5B646E5C4182" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_36382AFF497BE332B76EFC69E567533B_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_C24AD438216256CEBB0F5B646E5C4182" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_36382AFF497BE332B76EFC69E567533B_1BAB3C26B08E5CF7BC318B9BDED542AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FE1CCD35EDD85A298C2326D290D7EBD8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_C24AD438216256CEBB0F5B646E5C4182" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_FE1CCD35EDD85A298C2326D290D7EBD8" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_569C89B6BFFF522FA534EE1A63B74E36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_682517944B6D56BD82FD6DBF7F406A63" xlink:to="loc_dei_DocumentPeriodEndDate_569C89B6BFFF522FA534EE1A63B74E36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_CC1E388FD4F953D6A111FF09582696C7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_682517944B6D56BD82FD6DBF7F406A63" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_CC1E388FD4F953D6A111FF09582696C7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceRestrictedStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D964C8B67C2395EA90EA7E8776D4BD18" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D964C8B67C2395EA90EA7E8776D4BD18" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_0A7341AE73F7C0ABBB017E8776D49661" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D964C8B67C2395EA90EA7E8776D4BD18" xlink:to="loc_us-gaap_AwardTypeAxis_0A7341AE73F7C0ABBB017E8776D49661" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E01D7FEA26F2096CA8467E8776D47C89_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0A7341AE73F7C0ABBB017E8776D49661" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E01D7FEA26F2096CA8467E8776D47C89_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E01D7FEA26F2096CA8467E8776D47C89" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0A7341AE73F7C0ABBB017E8776D49661" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E01D7FEA26F2096CA8467E8776D47C89" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_KeyEmployeeRestrictedStockUnitsMember" xlink:label="loc_nx_KeyEmployeeRestrictedStockUnitsMember_1BFDBF7AC2DD3B7793767E8776D4F073" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E01D7FEA26F2096CA8467E8776D47C89" xlink:to="loc_nx_KeyEmployeeRestrictedStockUnitsMember_1BFDBF7AC2DD3B7793767E8776D4F073" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_PerformanceRestrictedStockUnitsMember" xlink:label="loc_nx_PerformanceRestrictedStockUnitsMember_1BFB3E38E0C0CEB36F637E8776D46838" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_E01D7FEA26F2096CA8467E8776D47C89" xlink:to="loc_nx_PerformanceRestrictedStockUnitsMember_1BFB3E38E0C0CEB36F637E8776D46838" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_182A605E76A97B183C4E7E8776D47787" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D964C8B67C2395EA90EA7E8776D4BD18" xlink:to="loc_srt_RangeAxis_182A605E76A97B183C4E7E8776D47787" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_6BB4FE16FA7B35A8486F7E8776D40DC7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_182A605E76A97B183C4E7E8776D47787" xlink:to="loc_srt_RangeMember_6BB4FE16FA7B35A8486F7E8776D40DC7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_6BB4FE16FA7B35A8486F7E8776D40DC7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_182A605E76A97B183C4E7E8776D47787" xlink:to="loc_srt_RangeMember_6BB4FE16FA7B35A8486F7E8776D40DC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_0625D8F327022811D1827E8776D43EB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6BB4FE16FA7B35A8486F7E8776D40DC7" xlink:to="loc_srt_MinimumMember_0625D8F327022811D1827E8776D43EB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_5B3F22A8B9C560E49DC87E8776D436DD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6BB4FE16FA7B35A8486F7E8776D40DC7" xlink:to="loc_srt_MaximumMember_5B3F22A8B9C560E49DC87E8776D436DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VestingAxis" xlink:label="loc_us-gaap_VestingAxis_390D818549471707E5187E8776D413CB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D964C8B67C2395EA90EA7E8776D4BD18" xlink:to="loc_us-gaap_VestingAxis_390D818549471707E5187E8776D413CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VestingDomain" xlink:label="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_390D818549471707E5187E8776D413CB" xlink:to="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_VestingDomain" xlink:label="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_390D818549471707E5187E8776D413CB" xlink:to="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_E7F974A51536424306577E8776D47402" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_E7F974A51536424306577E8776D47402" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_67D29AD9D973331A8B537E8776D40D8B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_67D29AD9D973331A8B537E8776D40D8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_7839DF13BE5135AF14967E8776D44353" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_7839DF13BE5135AF14967E8776D44353" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardTrancheFourMember" xlink:label="loc_nx_ShareBasedCompensationAwardTrancheFourMember_68FE8CE5F8F5BDFD7B3F7E8776D4124B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_22E398B48E7164305F2F7E8776D4DE8B" xlink:to="loc_nx_ShareBasedCompensationAwardTrancheFourMember_68FE8CE5F8F5BDFD7B3F7E8776D4124B" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAxis" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_BB9FACDDC4FC706A2A4B7E8776D46A46" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D964C8B67C2395EA90EA7E8776D4BD18" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_BB9FACDDC4FC706A2A4B7E8776D46A46" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaDomain" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_BB9FACDDC4FC706A2A4B7E8776D46A46" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060_default" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaDomain" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_BB9FACDDC4FC706A2A4B7E8776D46A46" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesGreaterThanOrEqualTo50PercentMember" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesGreaterThanOrEqualTo50PercentMember_A00D28F79CFDB46631347E8776D4DC35" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesGreaterThanOrEqualTo50PercentMember_A00D28F79CFDB46631347E8776D4DC35" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan50PercentAndGreaterThanOrEqualTo20PercentMember" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan50PercentAndGreaterThanOrEqualTo20PercentMember_690E5CA68964D35184F17E8776D43F3D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan50PercentAndGreaterThanOrEqualTo20PercentMember_690E5CA68964D35184F17E8776D43F3D" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan20PercentAndGreaterThanOrEqualToNegative20PercentMember" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan20PercentAndGreaterThanOrEqualToNegative20PercentMember_629CF2A3A7015D9E4F6D7E8776D43DA1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan20PercentAndGreaterThanOrEqualToNegative20PercentMember_629CF2A3A7015D9E4F6D7E8776D43DA1" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThanNegative20PercentMember" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThanNegative20PercentMember_DC869F6B1CC6610449497E8776D47873" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_CFE579AB2C570DE8CE5B7E8776D4E060" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThanNegative20PercentMember_DC869F6B1CC6610449497E8776D47873" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_3E3F5CAB5A15069EA9507E8776D4449C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_3E3F5CAB5A15069EA9507E8776D4449C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_EE824E775E4C30B5785B7E8776D43C42" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_EE824E775E4C30B5785B7E8776D43C42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_31FF483B3053F86983927E8776D4674A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_31FF483B3053F86983927E8776D4674A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_B74AF11F863EEF3F9CED7E8776D492BB" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_B74AF11F863EEF3F9CED7E8776D492BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_DF88FEA8EE214525F8137E8776E4E753" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_DF88FEA8EE214525F8137E8776E4E753" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F93D419D28D3294F4A167E8776E4F059" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F93D419D28D3294F4A167E8776E4F059" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_9EF6D2130F50000BB8A47E8776E4D657" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_C90902EC1248FB36DFBD7E8776D48DCF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_9EF6D2130F50000BB8A47E8776E4D657" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceShareAwardsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4C8020FABAE3FBC55B887E8776E420F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4C8020FABAE3FBC55B887E8776E420F3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardDateAxis" xlink:label="loc_us-gaap_AwardDateAxis_1664B5A0B26876E6DFEE7E8776E470BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4C8020FABAE3FBC55B887E8776E420F3" xlink:to="loc_us-gaap_AwardDateAxis_1664B5A0B26876E6DFEE7E8776E470BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaap_AwardDateDomain_218FF42ADE6CB1B5DB3C7E8776E46829_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_1664B5A0B26876E6DFEE7E8776E470BD" xlink:to="loc_us-gaap_AwardDateDomain_218FF42ADE6CB1B5DB3C7E8776E46829_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardDateDomain" xlink:label="loc_us-gaap_AwardDateDomain_218FF42ADE6CB1B5DB3C7E8776E46829" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_1664B5A0B26876E6DFEE7E8776E470BD" xlink:to="loc_us-gaap_AwardDateDomain_218FF42ADE6CB1B5DB3C7E8776E46829" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_BCC5F4EA93BCBBB6DE1F7E8776E4ABC3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4C8020FABAE3FBC55B887E8776E420F3" xlink:to="loc_us-gaap_AwardTypeAxis_BCC5F4EA93BCBBB6DE1F7E8776E4ABC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_BCC5F4EA93BCBBB6DE1F7E8776E4ABC3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_BCC5F4EA93BCBBB6DE1F7E8776E4ABC3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_2379C2EC3E2D97615BDA7E8776E4F870" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987" xlink:to="loc_us-gaap_PerformanceSharesMember_2379C2EC3E2D97615BDA7E8776E4F870" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_A217273C4F9BF7E8E1277E8776E4CDCE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_A217273C4F9BF7E8E1277E8776E4CDCE" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_PerformanceRestrictedStockUnitsMember" xlink:label="loc_nx_PerformanceRestrictedStockUnitsMember_2B829E519330909C7BA17E8776E48FF1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1B851917120F1EAB2AF27E8776E45987" xlink:to="loc_nx_PerformanceRestrictedStockUnitsMember_2B829E519330909C7BA17E8776E48FF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_1CB7AF98484787724B5C7E8776E4093E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4C8020FABAE3FBC55B887E8776E420F3" xlink:to="loc_srt_RangeAxis_1CB7AF98484787724B5C7E8776E4093E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_E3665A2B5FCDF55FD9047E8776E4EE76_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_1CB7AF98484787724B5C7E8776E4093E" xlink:to="loc_srt_RangeMember_E3665A2B5FCDF55FD9047E8776E4EE76_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_E3665A2B5FCDF55FD9047E8776E4EE76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_1CB7AF98484787724B5C7E8776E4093E" xlink:to="loc_srt_RangeMember_E3665A2B5FCDF55FD9047E8776E4EE76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_7F25CF43CBF06E2F8CD17E8776E40D2F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_E3665A2B5FCDF55FD9047E8776E4EE76" xlink:to="loc_srt_MinimumMember_7F25CF43CBF06E2F8CD17E8776E40D2F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_41F96AE4B45B95DA0CD87E8776E47DEC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_E3665A2B5FCDF55FD9047E8776E4EE76" xlink:to="loc_srt_MaximumMember_41F96AE4B45B95DA0CD87E8776E47DEC" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_PerformanceSharesSettledinCash" xlink:label="loc_nx_PerformanceSharesSettledinCash_12D3FECF2BC97079D5617E8776E436AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_nx_PerformanceSharesSettledinCash_12D3FECF2BC97079D5617E8776E436AF" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_PerformanceSharesSettledinStock" xlink:label="loc_nx_PerformanceSharesSettledinStock_268FD7C07FB7AE915EA97E8776E4EB73" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_nx_PerformanceSharesSettledinStock_268FD7C07FB7AE915EA97E8776E4EB73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationCashFlowEffectCashUsedToSettleAwards" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationCashFlowEffectCashUsedToSettleAwards_2DBCBB7DBAE5E22C15617E8776E48A08" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationCashFlowEffectCashUsedToSettleAwards_2DBCBB7DBAE5E22C15617E8776E48A08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_A3551F3DB557E813E4077E8776E4AA1C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_A3551F3DB557E813E4077E8776E4AA1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_15348600D6868CAF73907E8776E442B9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_15348600D6868CAF73907E8776E442B9" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_A2016PerformanceSharesVested" xlink:label="loc_nx_A2016PerformanceSharesVested_0302CD344B2196A3D1FB7E8776E48B5E" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_nx_A2016PerformanceSharesVested_0302CD344B2196A3D1FB7E8776E48B5E" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_Sharesgrantedforperformancesharevesting" xlink:label="loc_nx_Sharesgrantedforperformancesharevesting_01EE7034FCDEF4D1A1E47E8776E42B23" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_nx_Sharesgrantedforperformancesharevesting_01EE7034FCDEF4D1A1E47E8776E42B23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_0A55F97C49C49B512C337E8776E4C613" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_0A55F97C49C49B512C337E8776E4C613" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_D00D8E46CC5121FE96C07E8776E4C5BE" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_D00D8E46CC5121FE96C07E8776E4C5BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_7308E569085C042EC0257E8776E43A05" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_7308E569085C042EC0257E8776E43A05" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDiluted_FE89C0B740ACE1D0C5947E8776E45BA4" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDiluted_FE89C0B740ACE1D0C5947E8776E45BA4" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_RelativeTotalShareReturn" xlink:label="loc_nx_RelativeTotalShareReturn_482CE419ADF459B5370A7E8776E422F1" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_nx_RelativeTotalShareReturn_482CE419ADF459B5370A7E8776E422F1" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ReturnOnNetAssets" xlink:label="loc_nx_ReturnOnNetAssets_440644FC97A2B359A8017E8776E469EC" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_A686CA35ACA628D24B187E8776E4E726" xlink:to="loc_nx_ReturnOnNetAssets_440644FC97A2B359A8017E8776E469EC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockAwardsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_45F8CD4FF72D722A9A675E8A97A3010A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_45F8CD4FF72D722A9A675E8A97A3010A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_BA5187CA9A77C322D8D55E8A97A3BB81" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_45F8CD4FF72D722A9A675E8A97A3010A" xlink:to="loc_us-gaap_AwardTypeAxis_BA5187CA9A77C322D8D55E8A97A3BB81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_A665B484020CC2E2992F5E8A97A32BC3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_BA5187CA9A77C322D8D55E8A97A3BB81" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_A665B484020CC2E2992F5E8A97A32BC3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_A665B484020CC2E2992F5E8A97A32BC3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_BA5187CA9A77C322D8D55E8A97A3BB81" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_A665B484020CC2E2992F5E8A97A32BC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_F883EAF1474EBB10CF495E8A97A3F804" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_A665B484020CC2E2992F5E8A97A32BC3" xlink:to="loc_us-gaap_RestrictedStockMember_F883EAF1474EBB10CF495E8A97A3F804" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_AE6F0D5DB0F8E28936535E8A97A30AF7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_AE6F0D5DB0F8E28936535E8A97A30AF7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_F882B34DAC61BCA8A3275E8A97A3D73A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_AE6F0D5DB0F8E28936535E8A97A30AF7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_F882B34DAC61BCA8A3275E8A97A3D73A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_12636BB0A88864526BBD5E8A97B30A1D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_AE6F0D5DB0F8E28936535E8A97A30AF7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_12636BB0A88864526BBD5E8A97B30A1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_90B24124130BF02EF20C5E8A97B37658" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_AE6F0D5DB0F8E28936535E8A97A30AF7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_90B24124130BF02EF20C5E8A97B37658" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_96AF447899E4A310A2125E8A97B322FA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_AE6F0D5DB0F8E28936535E8A97A30AF7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_96AF447899E4A310A2125E8A97B322FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_057AEE110910565E00D15E8A97B3F47E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_057AEE110910565E00D15E8A97B3F47E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_FC9CC3FC60EF1C3484B05E8A97B3799F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_057AEE110910565E00D15E8A97B3F47E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_FC9CC3FC60EF1C3484B05E8A97B3799F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_D3C067F04AEB5F96B3465E8A97B393BB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_057AEE110910565E00D15E8A97B3F47E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_D3C067F04AEB5F96B3465E8A97B393BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_50C7E357FA1108B6EEF15E8A97B35D44" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_057AEE110910565E00D15E8A97B3F47E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_50C7E357FA1108B6EEF15E8A97B35D44" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_56694DFD2EBE4337E4255E8A97B3ECEF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_057AEE110910565E00D15E8A97B3F47E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_56694DFD2EBE4337E4255E8A97B3ECEF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_DB72DC1A75CDA9A827D55E8A97B39BFC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_DB72DC1A75CDA9A827D55E8A97B39BFC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_DFED0F578F9C66FDF1885E8A97B3E22B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_DFED0F578F9C66FDF1885E8A97B3E22B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_902D7FA6DBCF93AAE51C5E8A97B3EEFD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_900652E29CE826FA1C9F5E8A97A3573E" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_902D7FA6DBCF93AAE51C5E8A97B3EEFD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE07DF340F5B508EF5125E8A978D91D5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE07DF340F5B508EF5125E8A978D91D5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_4EBE0AF84AF0A2F10C305E8A978DB68F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_AE07DF340F5B508EF5125E8A978D91D5" xlink:to="loc_us-gaap_AwardTypeAxis_4EBE0AF84AF0A2F10C305E8A978DB68F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7B7D9E52F29AF11F17555E8A978D45C0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4EBE0AF84AF0A2F10C305E8A978DB68F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7B7D9E52F29AF11F17555E8A978D45C0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7B7D9E52F29AF11F17555E8A978D45C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4EBE0AF84AF0A2F10C305E8A978DB68F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7B7D9E52F29AF11F17555E8A978D45C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_D048B3E329FE21E216075E8A978DB41E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7B7D9E52F29AF11F17555E8A978D45C0" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_D048B3E329FE21E216075E8A978DB41E" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_KeyEmployeeRestrictedStockUnitsMember" xlink:label="loc_nx_KeyEmployeeRestrictedStockUnitsMember_6D78BF8A00B60D11C4FD5E8A978D616C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7B7D9E52F29AF11F17555E8A978D45C0" xlink:to="loc_nx_KeyEmployeeRestrictedStockUnitsMember_6D78BF8A00B60D11C4FD5E8A978D616C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_05E4300A91726B6521FF5E8A978D157B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_05E4300A91726B6521FF5E8A978D157B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2B790B19F93D7BAA72745E8A978D30FF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2B790B19F93D7BAA72745E8A978D30FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid_6EA1762B7B8093D379995E8A978DF26E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid_6EA1762B7B8093D379995E8A978DF26E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_8157924E738312AA0D065E8A978DB59D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_8157924E738312AA0D065E8A978DB59D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2BAA057E38FF54CE630A5E8A978D1F60" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_8157924E738312AA0D065E8A978DB59D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2BAA057E38FF54CE630A5E8A978D1F60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_70C0AC42A7A8DD357FD05E8A978D932F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_8157924E738312AA0D065E8A978DB59D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_70C0AC42A7A8DD357FD05E8A978D932F" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueAbstract" xlink:label="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueAbstract_78E8E61A3D04B0FEDC1F5E8A979D32F9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9B47FB988900C9D524F45E8A978D566D" xlink:to="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueAbstract_78E8E61A3D04B0FEDC1F5E8A979D32F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_DBBB4EC5394F4A2F8C755E8A979D1487" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueAbstract_78E8E61A3D04B0FEDC1F5E8A979D32F9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_DBBB4EC5394F4A2F8C755E8A979D1487" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_A256940FC5F173989F2E5E8A979D3D97" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValueAbstract_78E8E61A3D04B0FEDC1F5E8A979D32F9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_A256940FC5F173989F2E5E8A979D3D97" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationStockOptionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_576BA898A4D29A6F4FA65E8A97A3537A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7D18A473F48F97563DB55E8A97A36924" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_576BA898A4D29A6F4FA65E8A97A3537A" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7D18A473F48F97563DB55E8A97A36924" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_012BCC1ED1CD05CA26AC5E8A97A365D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7D18A473F48F97563DB55E8A97A36924" xlink:to="loc_us-gaap_AwardTypeAxis_012BCC1ED1CD05CA26AC5E8A97A365D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F20AA8EBFACD0155C3445E8A97A30F12_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_012BCC1ED1CD05CA26AC5E8A97A365D8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F20AA8EBFACD0155C3445E8A97A30F12_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F20AA8EBFACD0155C3445E8A97A30F12" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_012BCC1ED1CD05CA26AC5E8A97A365D8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F20AA8EBFACD0155C3445E8A97A30F12" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_F3F671A330E918E3CE2F5E8A97A3463F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F20AA8EBFACD0155C3445E8A97A30F12" xlink:to="loc_us-gaap_EmployeeStockOptionMember_F3F671A330E918E3CE2F5E8A97A3463F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_A06C1994BF9C1FF1B4235E8A97A395DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_576BA898A4D29A6F4FA65E8A97A3537A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_A06C1994BF9C1FF1B4235E8A97A395DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_FEDB1D2A4C00ED6370E55E8A97A3E3EE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_576BA898A4D29A6F4FA65E8A97A3537A" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_FEDB1D2A4C00ED6370E55E8A97A3E3EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_B82EB3CF6D8E7FC4C0885E8A97A3A794" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_576BA898A4D29A6F4FA65E8A97A3537A" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_B82EB3CF6D8E7FC4C0885E8A97A3A794" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTreasurySharesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_753F6EBFA1040673A6F75E8A975EA1EE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_868A1E45B67CA3B8E0065E8A975EBB1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_753F6EBFA1040673A6F75E8A975EA1EE" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_868A1E45B67CA3B8E0065E8A975EBB1F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_1A3F3EB76D7A58D644E75E8A975EC591" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_868A1E45B67CA3B8E0065E8A975EBB1F" xlink:to="loc_us-gaap_AwardTypeAxis_1A3F3EB76D7A58D644E75E8A975EC591" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_1A3F3EB76D7A58D644E75E8A975EC591" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_1A3F3EB76D7A58D644E75E8A975EC591" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_6875458929FE9E857D0A5E8A975EA583" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2" xlink:to="loc_us-gaap_RestrictedStockMember_6875458929FE9E857D0A5E8A975EA583" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_3CF67F85577DF1A08E805E8A975E1EC6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2" xlink:to="loc_us-gaap_PerformanceSharesMember_3CF67F85577DF1A08E805E8A975E1EC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_40CD696AD9FB54F6F3915E8A975EFE42" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6FC9F3BB954702E50FF55E8A975E2DA2" xlink:to="loc_us-gaap_EmployeeStockOptionMember_40CD696AD9FB54F6F3915E8A975EFE42" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_59D8A5B80574CEF640285E8A975E9E24" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_753F6EBFA1040673A6F75E8A975EA1EE" xlink:to="loc_dei_DocumentPeriodEndDate_59D8A5B80574CEF640285E8A975E9E24" xlink:type="arc" />
    <link:loc xlink:href="nx-20200131.xsd#nx_Deficiencyofstockoptionproceedsrecordedtoretainedearnings" xlink:label="loc_nx_Deficiencyofstockoptionproceedsrecordedtoretainedearnings_15EA17B7A3B4592091815E8A975E3297" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_753F6EBFA1040673A6F75E8A975EA1EE" xlink:to="loc_nx_Deficiencyofstockoptionproceedsrecordedtoretainedearnings_15EA17B7A3B4592091815E8A975E3297" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract" xlink:label="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_C74B70D2B4F1D50AE8B05E8A975E3C0F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_753F6EBFA1040673A6F75E8A975EA1EE" xlink:to="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_C74B70D2B4F1D50AE8B05E8A975E3C0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_2267DCD61EA648EB81DE5E8A975EEE73" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_C74B70D2B4F1D50AE8B05E8A975E3C0F" xlink:to="loc_us-gaap_TreasuryStockShares_2267DCD61EA648EB81DE5E8A975EEE73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F1DB8DEA920EB5B383155E8A975EFB1C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_C74B70D2B4F1D50AE8B05E8A975E3C0F" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F1DB8DEA920EB5B383155E8A975EFB1C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_DF4B447E13D67A68E51F5E8A975E8A36" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_C74B70D2B4F1D50AE8B05E8A975E3C0F" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_DF4B447E13D67A68E51F5E8A975E8A36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_51E6F2AEF6AC52A6D9955E8A975E3A7B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_C74B70D2B4F1D50AE8B05E8A975E3C0F" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_51E6F2AEF6AC52A6D9955E8A975E3A7B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/WarrantyObligations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/WarrantyObligationsDetail" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/WarrantyObligationsTables" xlink:type="extended" />
</link:linkbase>
