<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:29275be8-5f6e-4bc2-ad28-f39cf08543a0,g:6fd07fe1-7c2c-4ba2-863a-85996149b78d-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/Coverpage" xlink:type="simple" xlink:href="nx-20210131.xsd#Coverpage"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/Coverpage" xlink:type="extended" id="i845aff0f731d40408a2714bc65594683_Coverpage"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedBalanceSheetsUnaudited"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="extended" id="i82b066923d4f45daae355766a75a049f_CondensedConsolidatedBalanceSheetsUnaudited"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedBalanceSheetsUnauditedParenthetical"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" id="ib2e388573a2b4320a44ab57856b80eba_CondensedConsolidatedBalanceSheetsUnauditedParenthetical"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofIncomeLossUnaudited" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedStatementsofIncomeLossUnaudited"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofIncomeLossUnaudited" xlink:type="extended" id="i083cf84878444067bed34d44d3c7be70_CondensedConsolidatedStatementsofIncomeLossUnaudited"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofIncomeLossUnauditedParenthetical" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedStatementsofIncomeLossUnauditedParenthetical"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofIncomeLossUnauditedParenthetical" xlink:type="extended" id="iccc4fc0240ec45a29a0f1e54b94cb1ae_CondensedConsolidatedStatementsofIncomeLossUnauditedParenthetical"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeLossUnaudited" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedStatementsofComprehensiveIncomeLossUnaudited"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeLossUnaudited" xlink:type="extended" id="i7d3f6487e755458dae5225d6ba35fb02_CondensedConsolidatedStatementsofComprehensiveIncomeLossUnaudited"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofCashFlowUnaudited" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedStatementsofCashFlowUnaudited"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementsofCashFlowUnaudited" xlink:type="extended" id="ieeaf19094b4e4b878b73f64121cc128c_CondensedConsolidatedStatementsofCashFlowUnaudited"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementofStockholdersEquity" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedStatementofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementofStockholdersEquity" xlink:type="extended" id="i0797887b67e744aaacb90c50cd874555_CondensedConsolidatedStatementofStockholdersEquity">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_21e1d424-01f6-487b-bf9e-f405a5144d07" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_21e1d424-01f6-487b-bf9e-f405a5144d07" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_2482bd95-c64a-4af1-9c15-b29b1825f427" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_StockholdersEquity_2482bd95-c64a-4af1-9c15-b29b1825f427" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_649c8be2-e2b6-48b0-abc9-66208579a762" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_NetIncomeLoss_649c8be2-e2b6-48b0-abc9-66208579a762" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_f801040c-6995-461b-a431-ed2a1aace0cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_f801040c-6995-461b-a431-ed2a1aace0cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_af568ace-8942-40f3-bd1a-90234ffd38f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_DividendsCommonStockCash_af568ace-8942-40f3-bd1a-90234ffd38f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_3f4c3b2c-0832-45ef-9abe-5ceab12ee0df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_3f4c3b2c-0832-45ef-9abe-5ceab12ee0df" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_f4deb0ae-4fd7-45ea-813e-f4924bd0191e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax_f4deb0ae-4fd7-45ea-813e-f4924bd0191e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAbstract_801fc321-afd6-4326-b93b-7705764cc8bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_ShareBasedCompensationAbstract_801fc321-afd6-4326-b93b-7705764cc8bc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_bf3895df-77f8-43a2-a0e0-4bbf7b59ed62" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_801fc321-afd6-4326-b93b-7705764cc8bc" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_bf3895df-77f8-43a2-a0e0-4bbf7b59ed62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_f21b6b62-93ba-4849-95cc-5b2618c05da7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_801fc321-afd6-4326-b93b-7705764cc8bc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_f21b6b62-93ba-4849-95cc-5b2618c05da7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_0b1cc6fa-3d8b-45ae-9059-3893d20cfdbb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_801fc321-afd6-4326-b93b-7705764cc8bc" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_0b1cc6fa-3d8b-45ae-9059-3893d20cfdbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_StockIssuedDuringPeriodTreasurySharesPerformanceSharesVested_11795044-a12f-4e95-9f0e-c1185a5bfee1" xlink:href="nx-20210131.xsd#nx_StockIssuedDuringPeriodTreasurySharesPerformanceSharesVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationAbstract_801fc321-afd6-4326-b93b-7705764cc8bc" xlink:to="loc_nx_StockIssuedDuringPeriodTreasurySharesPerformanceSharesVested_11795044-a12f-4e95-9f0e-c1185a5bfee1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_bb2376fa-a0b3-4fa2-bd4d-190145b85a67" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_9efe1143-8009-4d23-b250-328deadbabe2" xlink:to="loc_us-gaap_StockholdersEquityOther_bb2376fa-a0b3-4fa2-bd4d-190145b85a67" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_a094d822-953e-46f4-b13a-bf38d63f5c78" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_326ebe96-ff8c-49f9-9b6f-fd411bc46743" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_21e1d424-01f6-487b-bf9e-f405a5144d07" xlink:to="loc_us-gaap_StatementTable_326ebe96-ff8c-49f9-9b6f-fd411bc46743" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_35815aaf-5ec1-4b02-9061-ab41feab0e5c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_326ebe96-ff8c-49f9-9b6f-fd411bc46743" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_35815aaf-5ec1-4b02-9061-ab41feab0e5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_35815aaf-5ec1-4b02-9061-ab41feab0e5c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_35815aaf-5ec1-4b02-9061-ab41feab0e5c" xlink:to="loc_us-gaap_EquityComponentDomain_35815aaf-5ec1-4b02-9061-ab41feab0e5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_35815aaf-5ec1-4b02-9061-ab41feab0e5c" xlink:to="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_55fc691a-7499-43e7-84c5-f38be29e4f62" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:to="loc_us-gaap_CommonStockMember_55fc691a-7499-43e7-84c5-f38be29e4f62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_189a4887-1bb1-4a75-b488-9d7fa604c5ea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_189a4887-1bb1-4a75-b488-9d7fa604c5ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_29bbf025-5703-4a41-8275-3f6d958a25e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:to="loc_us-gaap_RetainedEarningsMember_29bbf025-5703-4a41-8275-3f6d958a25e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_518bc821-6599-4f84-8275-8853f0e31df0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_518bc821-6599-4f84-8275-8853f0e31df0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_c19da391-7ad9-4ad5-ab6a-bd6274db8a89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_03f9b27e-17e7-4042-8e6e-9d9d33b4df83" xlink:to="loc_us-gaap_TreasuryStockMember_c19da391-7ad9-4ad5-ab6a-bd6274db8a89" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementofStockholdersEquityParenthetical" xlink:type="simple" xlink:href="nx-20210131.xsd#CondensedConsolidatedStatementofStockholdersEquityParenthetical"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/CondensedConsolidatedStatementofStockholdersEquityParenthetical" xlink:type="extended" id="if476ab6bb16e453aa955ee9536000c1f_CondensedConsolidatedStatementofStockholdersEquityParenthetical"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureofOperationsandBasisofPresentation" xlink:type="simple" xlink:href="nx-20210131.xsd#NatureofOperationsandBasisofPresentation"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureofOperationsandBasisofPresentation" xlink:type="extended" id="i7a79d0db89fd466bb5da8c920a82772a_NatureofOperationsandBasisofPresentation"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureofOperationsandBasisofPresentationTables" xlink:type="simple" xlink:href="nx-20210131.xsd#NatureofOperationsandBasisofPresentationTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureofOperationsandBasisofPresentationTables" xlink:type="extended" id="i1cd718fab72d4f35868ce756c594b872_NatureofOperationsandBasisofPresentationTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NatureofOperationsandBasisofPresentationSummaryofProductSalesDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#NatureofOperationsandBasisofPresentationSummaryofProductSalesDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NatureofOperationsandBasisofPresentationSummaryofProductSalesDetails" xlink:type="extended" id="ie64ec1b34932490d9bdfafbea1f66c19_NatureofOperationsandBasisofPresentationSummaryofProductSalesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductInformationLineItems_09eec1d0-e94d-4221-87f8-d2ffa7d7df52" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProductInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_faad7c74-439a-4467-a3b6-16cb59c5829a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_09eec1d0-e94d-4221-87f8-d2ffa7d7df52" xlink:to="loc_us-gaap_NumberOfReportableSegments_faad7c74-439a-4467-a3b6-16cb59c5829a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_2fd88607-6ed7-45b5-98ad-41417c073e3e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_09eec1d0-e94d-4221-87f8-d2ffa7d7df52" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_2fd88607-6ed7-45b5-98ad-41417c073e3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfProductInformationTable_dbcad7e0-d37e-4ffe-a780-4a4228d627a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfProductInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductInformationLineItems_09eec1d0-e94d-4221-87f8-d2ffa7d7df52" xlink:to="loc_us-gaap_ScheduleOfProductInformationTable_dbcad7e0-d37e-4ffe-a780-4a4228d627a0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_6392c524-a18e-48c1-9e2a-d532d0825c88" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_dbcad7e0-d37e-4ffe-a780-4a4228d627a0" xlink:to="loc_srt_ConsolidationItemsAxis_6392c524-a18e-48c1-9e2a-d532d0825c88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_6392c524-a18e-48c1-9e2a-d532d0825c88_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_6392c524-a18e-48c1-9e2a-d532d0825c88" xlink:to="loc_srt_ConsolidationItemsDomain_6392c524-a18e-48c1-9e2a-d532d0825c88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_d87a2827-c23e-465c-8e40-81959af88997" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_6392c524-a18e-48c1-9e2a-d532d0825c88" xlink:to="loc_srt_ConsolidationItemsDomain_d87a2827-c23e-465c-8e40-81959af88997" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_e7026aa6-3d5e-4f97-a3ca-5bce8bfd12a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_d87a2827-c23e-465c-8e40-81959af88997" xlink:to="loc_us-gaap_OperatingSegmentsMember_e7026aa6-3d5e-4f97-a3ca-5bce8bfd12a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_6b26d38b-08db-4fda-92b1-1cc4648cc6c7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_d87a2827-c23e-465c-8e40-81959af88997" xlink:to="loc_us-gaap_CorporateNonSegmentMember_6b26d38b-08db-4fda-92b1-1cc4648cc6c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_93192f83-7f0b-4eaf-98d0-b384cb7b169a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_dbcad7e0-d37e-4ffe-a780-4a4228d627a0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_93192f83-7f0b-4eaf-98d0-b384cb7b169a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_93192f83-7f0b-4eaf-98d0-b384cb7b169a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_93192f83-7f0b-4eaf-98d0-b384cb7b169a" xlink:to="loc_us-gaap_SegmentDomain_93192f83-7f0b-4eaf-98d0-b384cb7b169a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1c8faae2-7d43-4df5-90b2-8e0b2a2a7afb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_93192f83-7f0b-4eaf-98d0-b384cb7b169a" xlink:to="loc_us-gaap_SegmentDomain_1c8faae2-7d43-4df5-90b2-8e0b2a2a7afb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NAEngineeredComponentsMember_eb1fda6a-cc3d-4a23-980e-925e40902f25" xlink:href="nx-20210131.xsd#nx_NAEngineeredComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1c8faae2-7d43-4df5-90b2-8e0b2a2a7afb" xlink:to="loc_nx_NAEngineeredComponentsMember_eb1fda6a-cc3d-4a23-980e-925e40902f25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_EUEngineeredComponentsMember_dec5314c-8431-4a06-9c5f-61195dcd28e4" xlink:href="nx-20210131.xsd#nx_EUEngineeredComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1c8faae2-7d43-4df5-90b2-8e0b2a2a7afb" xlink:to="loc_nx_EUEngineeredComponentsMember_dec5314c-8431-4a06-9c5f-61195dcd28e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NACabinetComponentsMember_d4495e36-cf94-4afa-86e0-0600c4ffbb64" xlink:href="nx-20210131.xsd#nx_NACabinetComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_1c8faae2-7d43-4df5-90b2-8e0b2a2a7afb" xlink:to="loc_nx_NACabinetComponentsMember_d4495e36-cf94-4afa-86e0-0600c4ffbb64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_5ef2232c-d722-455f-a7ea-04b2e41b4566" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_dbcad7e0-d37e-4ffe-a780-4a4228d627a0" xlink:to="loc_srt_StatementGeographicalAxis_5ef2232c-d722-455f-a7ea-04b2e41b4566" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_5ef2232c-d722-455f-a7ea-04b2e41b4566_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_5ef2232c-d722-455f-a7ea-04b2e41b4566" xlink:to="loc_srt_SegmentGeographicalDomain_5ef2232c-d722-455f-a7ea-04b2e41b4566_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_cc961486-5c12-4820-ad63-f190bb6805fc" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_5ef2232c-d722-455f-a7ea-04b2e41b4566" xlink:to="loc_srt_SegmentGeographicalDomain_cc961486-5c12-4820-ad63-f190bb6805fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_InternationalMember_559f1b2d-a5fc-46fb-ba6b-c46f3528c651" xlink:href="nx-20210131.xsd#nx_InternationalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_cc961486-5c12-4820-ad63-f190bb6805fc" xlink:to="loc_nx_InternationalMember_559f1b2d-a5fc-46fb-ba6b-c46f3528c651" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_684d28dd-eb2c-45b4-ab59-94767e6668d3" xlink:href="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_cc961486-5c12-4820-ad63-f190bb6805fc" xlink:to="loc_country_US_684d28dd-eb2c-45b4-ab59-94767e6668d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_cbda6dcf-c425-4f93-ac9e-b204626313c7" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_dbcad7e0-d37e-4ffe-a780-4a4228d627a0" xlink:to="loc_srt_ProductOrServiceAxis_cbda6dcf-c425-4f93-ac9e-b204626313c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_cbda6dcf-c425-4f93-ac9e-b204626313c7_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_cbda6dcf-c425-4f93-ac9e-b204626313c7" xlink:to="loc_srt_ProductsAndServicesDomain_cbda6dcf-c425-4f93-ac9e-b204626313c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_0b1f14e0-f022-42df-9fb2-926269a346ad" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_cbda6dcf-c425-4f93-ac9e-b204626313c7" xlink:to="loc_srt_ProductsAndServicesDomain_0b1f14e0-f022-42df-9fb2-926269a346ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NonfenestrationMember_f1c04f1f-c18f-4793-bf17-4e2fac64b5d7" xlink:href="nx-20210131.xsd#nx_NonfenestrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_0b1f14e0-f022-42df-9fb2-926269a346ad" xlink:to="loc_nx_NonfenestrationMember_f1c04f1f-c18f-4793-bf17-4e2fac64b5d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_FenestrationMember_b3675277-02ae-46cd-a738-cc9947ce3167" xlink:href="nx-20210131.xsd#nx_FenestrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_0b1f14e0-f022-42df-9fb2-926269a346ad" xlink:to="loc_nx_FenestrationMember_b3675277-02ae-46cd-a738-cc9947ce3167" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/Inventories" xlink:type="simple" xlink:href="nx-20210131.xsd#Inventories"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/Inventories" xlink:type="extended" id="i8619c608d7a148b5bd319018345aea2e_Inventories"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/InventoriesTables" xlink:type="simple" xlink:href="nx-20210131.xsd#InventoriesTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/InventoriesTables" xlink:type="extended" id="i89b1553678174a06ae9479e9f38682c3_InventoriesTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/InventoriesDetail" xlink:type="simple" xlink:href="nx-20210131.xsd#InventoriesDetail"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/InventoriesDetail" xlink:type="extended" id="iac1ad1902c6b4924b8a7f1aa28d06f8f_InventoriesDetail"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssets" xlink:type="simple" xlink:href="nx-20210131.xsd#GoodwillandIntangibleAssets"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssets" xlink:type="extended" id="i3c131d10f18246ee944a89c589c69e21_GoodwillandIntangibleAssets"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssetsTables" xlink:type="simple" xlink:href="nx-20210131.xsd#GoodwillandIntangibleAssetsTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssetsTables" xlink:type="extended" id="ic6774f7a95484283833f8f76c217e4a7_GoodwillandIntangibleAssetsTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssetsGoodwillDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#GoodwillandIntangibleAssetsGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssetsGoodwillDetails" xlink:type="extended" id="if11ebc59da2e404ab0d2405c0409f488_GoodwillandIntangibleAssetsGoodwillDetails"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssetsIdentifiableIntangibleAssetsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#GoodwillandIntangibleAssetsIdentifiableIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/GoodwillandIntangibleAssetsIdentifiableIntangibleAssetsDetails" xlink:type="extended" id="i6d4ada0d845846ce973e46071d092d9b_GoodwillandIntangibleAssetsIdentifiableIntangibleAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_45b823c4-14fd-4944-a1e7-1881ffadf222" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_48857372-b0c8-4181-aa7a-74e8002132fb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_45b823c4-14fd-4944-a1e7-1881ffadf222" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_48857372-b0c8-4181-aa7a-74e8002132fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_ea398a43-602e-4a7b-b552-be958bfb8163" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_45b823c4-14fd-4944-a1e7-1881ffadf222" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_ea398a43-602e-4a7b-b552-be958bfb8163" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_01419d3d-e047-41ac-8928-e00fe568617e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_45b823c4-14fd-4944-a1e7-1881ffadf222" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_01419d3d-e047-41ac-8928-e00fe568617e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_275f029b-bdfb-4b29-946f-a0d339faec80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_45b823c4-14fd-4944-a1e7-1881ffadf222" xlink:to="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_275f029b-bdfb-4b29-946f-a0d339faec80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_b2b2739c-707a-4f69-961c-f56e147dd84d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_45b823c4-14fd-4944-a1e7-1881ffadf222" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_b2b2739c-707a-4f69-961c-f56e147dd84d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e13506f5-ddaf-4b65-867a-6d8d2a71a699" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_b2b2739c-707a-4f69-961c-f56e147dd84d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e13506f5-ddaf-4b65-867a-6d8d2a71a699" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e13506f5-ddaf-4b65-867a-6d8d2a71a699_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e13506f5-ddaf-4b65-867a-6d8d2a71a699" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e13506f5-ddaf-4b65-867a-6d8d2a71a699_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ce9dd1d2-0c36-4e85-ad12-91d0578086ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e13506f5-ddaf-4b65-867a-6d8d2a71a699" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ce9dd1d2-0c36-4e85-ad12-91d0578086ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_950dfcc6-9549-42d5-9c07-8ae087f31288" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ce9dd1d2-0c36-4e85-ad12-91d0578086ac" xlink:to="loc_us-gaap_CustomerRelationshipsMember_950dfcc6-9549-42d5-9c07-8ae087f31288" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_TradenamesAndTrademarksMember_9c237292-0010-4067-96f1-c42a66f71f0a" xlink:href="nx-20210131.xsd#nx_TradenamesAndTrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ce9dd1d2-0c36-4e85-ad12-91d0578086ac" xlink:to="loc_nx_TradenamesAndTrademarksMember_9c237292-0010-4067-96f1-c42a66f71f0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_PatentsAndOtherTechnologyMember_9e7d2548-09d3-4346-81be-ce40fd1836ed" xlink:href="nx-20210131.xsd#nx_PatentsAndOtherTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ce9dd1d2-0c36-4e85-ad12-91d0578086ac" xlink:to="loc_nx_PatentsAndOtherTechnologyMember_9e7d2548-09d3-4346-81be-ce40fd1836ed" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DebtandFinanceLeaseObligations" xlink:type="simple" xlink:href="nx-20210131.xsd#DebtandFinanceLeaseObligations"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DebtandFinanceLeaseObligations" xlink:type="extended" id="i0d681753ac2049828fd2b66722002b37_DebtandFinanceLeaseObligations"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DebtandFinanceLeaseObligationsTables" xlink:type="simple" xlink:href="nx-20210131.xsd#DebtandFinanceLeaseObligationsTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DebtandFinanceLeaseObligationsTables" xlink:type="extended" id="ia506490be2194319ae60f0eab2c23cef_DebtandFinanceLeaseObligationsTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/DebtandFinanceLeaseObligationsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#DebtandFinanceLeaseObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/DebtandFinanceLeaseObligationsDetails" xlink:type="extended" id="iafe0178988f640e4aafb7ea9a28f0b5b_DebtandFinanceLeaseObligationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:href="nx-20210131.xsd#nx_DebtDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_144e93c4-e5a6-4623-8c87-6fd398550f7b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_144e93c4-e5a6-4623-8c87-6fd398550f7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_36dd8b17-1d04-43ff-b7d2-b44a7989c936" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_36dd8b17-1d04-43ff-b7d2-b44a7989c936" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_16488201-cbf3-4f04-9edb-26d9afad82ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_16488201-cbf3-4f04-9edb-26d9afad82ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_3d56d3c3-2f5a-4764-b5cd-adaf457ddd62" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_3d56d3c3-2f5a-4764-b5cd-adaf457ddd62" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_LineofCreditFacilityMaximumBorrowingCapacityCommittedAmount_435462ae-f157-4e8f-833f-bee8e8473931" xlink:href="nx-20210131.xsd#nx_LineofCreditFacilityMaximumBorrowingCapacityCommittedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_LineofCreditFacilityMaximumBorrowingCapacityCommittedAmount_435462ae-f157-4e8f-833f-bee8e8473931" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_c4b40681-6de4-489f-a0ea-61872a748dc8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_c4b40681-6de4-489f-a0ea-61872a748dc8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_f42957a0-e34d-4e75-86a9-361e763917c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_f42957a0-e34d-4e75-86a9-361e763917c6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtInstrumentDebtDefaultInterestAccrualRate_483e866e-775c-4a8a-8ea9-887f7b407d32" xlink:href="nx-20210131.xsd#nx_DebtInstrumentDebtDefaultInterestAccrualRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_DebtInstrumentDebtDefaultInterestAccrualRate_483e866e-775c-4a8a-8ea9-887f7b407d32" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_MinimumIncrementalBorrowing_39e9f106-cd0b-4989-a449-401ab943c78a" xlink:href="nx-20210131.xsd#nx_MinimumIncrementalBorrowing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_MinimumIncrementalBorrowing_39e9f106-cd0b-4989-a449-401ab943c78a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_MaximumIncrementalBorrowing_e65a054b-0f46-4624-9bc4-257a2fb55f2d" xlink:href="nx-20210131.xsd#nx_MaximumIncrementalBorrowing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_MaximumIncrementalBorrowing_e65a054b-0f46-4624-9bc4-257a2fb55f2d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_ccfcd574-2fcc-4976-9f79-77ee8e3a3b74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_ccfcd574-2fcc-4976-9f79-77ee8e3a3b74" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtInstrumentRequiredCoverageRatio_426f4428-11c1-4428-90f6-d893c6dbd502" xlink:href="nx-20210131.xsd#nx_DebtInstrumentRequiredCoverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_DebtInstrumentRequiredCoverageRatio_426f4428-11c1-4428-90f6-d893c6dbd502" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtInstrumentRequiredLeverageRatio_99727577-e2f2-4d26-b042-5033137c182a" xlink:href="nx-20210131.xsd#nx_DebtInstrumentRequiredLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_DebtInstrumentRequiredLeverageRatio_99727577-e2f2-4d26-b042-5033137c182a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtInstrumentLimitationonAnnualDividend_fde1c204-e65a-4751-8ed6-a1c2195fcdd5" xlink:href="nx-20210131.xsd#nx_DebtInstrumentLimitationonAnnualDividend"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_DebtInstrumentLimitationonAnnualDividend_fde1c204-e65a-4751-8ed6-a1c2195fcdd5" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtInstrumentLeverageRatioThresholdforLimitationstoTakeEffect_1496f11c-e892-4d60-b700-a04b31826e85" xlink:href="nx-20210131.xsd#nx_DebtInstrumentLeverageRatioThresholdforLimitationstoTakeEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_DebtInstrumentLeverageRatioThresholdforLimitationstoTakeEffect_1496f11c-e892-4d60-b700-a04b31826e85" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_DebtInstrumentLiquidityThresholdforLimitationstoTakeEffect_b2b03627-007e-4e21-844a-5fccfcb75bb5" xlink:href="nx-20210131.xsd#nx_DebtInstrumentLiquidityThresholdforLimitationstoTakeEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_nx_DebtInstrumentLiquidityThresholdforLimitationstoTakeEffect_b2b03627-007e-4e21-844a-5fccfcb75bb5" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_8e5e5283-1aa5-4f7f-9e2d-63f6a975e39b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_LineOfCredit_8e5e5283-1aa5-4f7f-9e2d-63f6a975e39b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_1bf84f68-61ca-48a9-a36c-0d535e6c778a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_1bf84f68-61ca-48a9-a36c-0d535e6c778a" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLongTermDebt_6eb5424e-ed5e-4366-b774-493f7953208f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_OtherLongTermDebt_6eb5424e-ed5e-4366-b774-493f7953208f" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_5130dac3-f22a-4b2b-9e77-a3bd128c2d9b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_5130dac3-f22a-4b2b-9e77-a3bd128c2d9b" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_6fb78b8d-096f-4b8f-990f-4efc87a74f4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_6fb78b8d-096f-4b8f-990f-4efc87a74f4c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_ecfec9da-e92c-4137-a9a3-61cc5ff831d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_ecfec9da-e92c-4137-a9a3-61cc5ff831d6" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_b3b79f35-f78d-448e-8b61-1f1b44783a76" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nx_DebtDisclosureLineItems_d2f77c67-fe4d-4535-a06c-af593c3affb2" xlink:to="loc_us-gaap_DebtInstrumentTable_b3b79f35-f78d-448e-8b61-1f1b44783a76" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_31a8fb8a-3a46-4106-b338-6188df387d98" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b3b79f35-f78d-448e-8b61-1f1b44783a76" xlink:to="loc_us-gaap_VariableRateAxis_31a8fb8a-3a46-4106-b338-6188df387d98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_31a8fb8a-3a46-4106-b338-6188df387d98_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_31a8fb8a-3a46-4106-b338-6188df387d98" xlink:to="loc_us-gaap_VariableRateDomain_31a8fb8a-3a46-4106-b338-6188df387d98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_44138c56-5fc6-4fd1-8bf5-9add9dfd0651" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_31a8fb8a-3a46-4106-b338-6188df387d98" xlink:to="loc_us-gaap_VariableRateDomain_44138c56-5fc6-4fd1-8bf5-9add9dfd0651" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_b855ee59-f073-4cf6-af0d-f90408bc15f2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_44138c56-5fc6-4fd1-8bf5-9add9dfd0651" xlink:to="loc_us-gaap_BaseRateMember_b855ee59-f073-4cf6-af0d-f90408bc15f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_a63832d4-9fc8-401e-8b20-d88f64f5316a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_44138c56-5fc6-4fd1-8bf5-9add9dfd0651" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_a63832d4-9fc8-401e-8b20-d88f64f5316a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_7092d7f7-05b9-441b-8391-52daa18d1b2f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b3b79f35-f78d-448e-8b61-1f1b44783a76" xlink:to="loc_us-gaap_CreditFacilityAxis_7092d7f7-05b9-441b-8391-52daa18d1b2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_7092d7f7-05b9-441b-8391-52daa18d1b2f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_7092d7f7-05b9-441b-8391-52daa18d1b2f" xlink:to="loc_us-gaap_CreditFacilityDomain_7092d7f7-05b9-441b-8391-52daa18d1b2f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_0f8a20ff-fde9-4438-abdc-c6b67e476b96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_7092d7f7-05b9-441b-8391-52daa18d1b2f" xlink:to="loc_us-gaap_CreditFacilityDomain_0f8a20ff-fde9-4438-abdc-c6b67e476b96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_A2018CreditFacilityMember_0a4423e6-ad2d-4b3b-bd7e-9b31e1c8fa48" xlink:href="nx-20210131.xsd#nx_A2018CreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0f8a20ff-fde9-4438-abdc-c6b67e476b96" xlink:to="loc_nx_A2018CreditFacilityMember_0a4423e6-ad2d-4b3b-bd7e-9b31e1c8fa48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_6a050e6e-0324-4e72-ad03-b853f4417cd4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0f8a20ff-fde9-4438-abdc-c6b67e476b96" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_6a050e6e-0324-4e72-ad03-b853f4417cd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_TermLoanFacilityMember_cc0f8dd1-0de7-4e12-a3bb-5c9751a51318" xlink:href="nx-20210131.xsd#nx_TermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0f8a20ff-fde9-4438-abdc-c6b67e476b96" xlink:to="loc_nx_TermLoanFacilityMember_cc0f8dd1-0de7-4e12-a3bb-5c9751a51318" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_SwingLineMember_001796d7-11d4-48ff-ad73-34f45a2fa9d4" xlink:href="nx-20210131.xsd#nx_SwingLineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_0f8a20ff-fde9-4438-abdc-c6b67e476b96" xlink:to="loc_nx_SwingLineMember_001796d7-11d4-48ff-ad73-34f45a2fa9d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_502f0179-3697-485d-b663-3fa18b9d5d56" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b3b79f35-f78d-448e-8b61-1f1b44783a76" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_502f0179-3697-485d-b663-3fa18b9d5d56" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_502f0179-3697-485d-b663-3fa18b9d5d56_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_502f0179-3697-485d-b663-3fa18b9d5d56" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_502f0179-3697-485d-b663-3fa18b9d5d56_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5dd920c9-967f-45cf-ac62-e717e9c52a74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_502f0179-3697-485d-b663-3fa18b9d5d56" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5dd920c9-967f-45cf-ac62-e717e9c52a74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_TermLoanFacilityMember_d1257305-ede6-4cae-910f-06c33b196e62" xlink:href="nx-20210131.xsd#nx_TermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5dd920c9-967f-45cf-ac62-e717e9c52a74" xlink:to="loc_nx_TermLoanFacilityMember_d1257305-ede6-4cae-910f-06c33b196e62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_49c18ae5-21fb-4bdb-8457-e73570b7481c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5dd920c9-967f-45cf-ac62-e717e9c52a74" xlink:to="loc_us-gaap_LineOfCreditMember_49c18ae5-21fb-4bdb-8457-e73570b7481c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_CapitalLeaseObligationsAndOtherMember_6c482c93-b7a3-4180-9b97-3f28c11eb9a5" xlink:href="nx-20210131.xsd#nx_CapitalLeaseObligationsAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5dd920c9-967f-45cf-ac62-e717e9c52a74" xlink:to="loc_nx_CapitalLeaseObligationsAndOtherMember_6c482c93-b7a3-4180-9b97-3f28c11eb9a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_cce4a9f5-0657-49f5-b60e-6c1ae2acb34c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5dd920c9-967f-45cf-ac62-e717e9c52a74" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_cce4a9f5-0657-49f5-b60e-6c1ae2acb34c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_08353ee6-7436-44cb-9329-4ced5148b736" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_08353ee6-7436-44cb-9329-4ced5148b736_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_bd50d353-0d9c-4b27-9288-73dd45678e7a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_47613274-4f29-4962-a931-85a26ce9801c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_0502f88d-d6ed-42be-9453-e11454c24363" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_InterestRateScenarioAxis_38d45a75-3165-429a-b0ad-46ccb25abe9d" xlink:href="nx-20210131.xsd#nx_InterestRateScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b3b79f35-f78d-448e-8b61-1f1b44783a76" xlink:to="loc_nx_InterestRateScenarioAxis_38d45a75-3165-429a-b0ad-46ccb25abe9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_InterestRateScenarioDomain_38d45a75-3165-429a-b0ad-46ccb25abe9d_default" xlink:href="nx-20210131.xsd#nx_InterestRateScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nx_InterestRateScenarioAxis_38d45a75-3165-429a-b0ad-46ccb25abe9d" xlink:to="loc_nx_InterestRateScenarioDomain_38d45a75-3165-429a-b0ad-46ccb25abe9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_InterestRateScenarioDomain_3db837d8-9d45-4f1b-847d-359a6cc719bf" xlink:href="nx-20210131.xsd#nx_InterestRateScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nx_InterestRateScenarioAxis_38d45a75-3165-429a-b0ad-46ccb25abe9d" xlink:to="loc_nx_InterestRateScenarioDomain_3db837d8-9d45-4f1b-847d-359a6cc719bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_LessThanOneandOneHalfLeverageRatioMember_ba6d1cb1-9351-49af-b6da-a376f5e30943" xlink:href="nx-20210131.xsd#nx_LessThanOneandOneHalfLeverageRatioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_3db837d8-9d45-4f1b-847d-359a6cc719bf" xlink:to="loc_nx_LessThanOneandOneHalfLeverageRatioMember_ba6d1cb1-9351-49af-b6da-a376f5e30943" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_8420d326-d6b5-41a3-a056-35f6c8714dd6" xlink:href="nx-20210131.xsd#nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_3db837d8-9d45-4f1b-847d-359a6cc719bf" xlink:to="loc_nx_BetweenOneandOneHalfandTwoandOneQuarterLeverageRatioMember_8420d326-d6b5-41a3-a056-35f6c8714dd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_1d27f4a3-ff8b-443a-b2d2-875733a3a99d" xlink:href="nx-20210131.xsd#nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_3db837d8-9d45-4f1b-847d-359a6cc719bf" xlink:to="loc_nx_BetweenTwoandOneQuarterandThreeLeverageRatioMember_1d27f4a3-ff8b-443a-b2d2-875733a3a99d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_GreaterThanThreeLeverageRatioMember_9b82e632-b8fd-489e-86d7-980ab2629fad" xlink:href="nx-20210131.xsd#nx_GreaterThanThreeLeverageRatioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_InterestRateScenarioDomain_3db837d8-9d45-4f1b-847d-359a6cc719bf" xlink:to="loc_nx_GreaterThanThreeLeverageRatioMember_9b82e632-b8fd-489e-86d7-980ab2629fad" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/RetirementPlans" xlink:type="simple" xlink:href="nx-20210131.xsd#RetirementPlans"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/RetirementPlans" xlink:type="extended" id="ia28c2384224f4d73be54547efd7b3a52_RetirementPlans"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/RetirementPlansTables" xlink:type="simple" xlink:href="nx-20210131.xsd#RetirementPlansTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/RetirementPlansTables" xlink:type="extended" id="i76b0bc8d55a04f3bb28052703baf5be5_RetirementPlansTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/RetirementPlansDetail" xlink:type="simple" xlink:href="nx-20210131.xsd#RetirementPlansDetail"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/RetirementPlansDetail" xlink:type="extended" id="id5dd2c15a5fe46f0a59090c59dd08c52_RetirementPlansDetail"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/IncomeTaxes" xlink:type="simple" xlink:href="nx-20210131.xsd#IncomeTaxes"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/IncomeTaxes" xlink:type="extended" id="i9d21215775384f0485c0410b781838ef_IncomeTaxes"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/IncomeTaxesDetail" xlink:type="simple" xlink:href="nx-20210131.xsd#IncomeTaxesDetail"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/IncomeTaxesDetail" xlink:type="extended" id="ibb6019a4c52a468898e63368b55b49ae_IncomeTaxesDetail"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/Contingencies" xlink:type="simple" xlink:href="nx-20210131.xsd#Contingencies"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/Contingencies" xlink:type="extended" id="ie6dd2b5261d84af08186a3acbe1abcdf_Contingencies"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/FairValueMeasurementofAssetsandLiabilities" xlink:type="simple" xlink:href="nx-20210131.xsd#FairValueMeasurementofAssetsandLiabilities"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/FairValueMeasurementofAssetsandLiabilities" xlink:type="extended" id="i0c7d9d285687489abbb57843c421e164_FairValueMeasurementofAssetsandLiabilities"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensation" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensation"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensation" xlink:type="extended" id="i33b6eb7ddcf74c9e9b2f476b092b26bd_StockBasedCompensation"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTables" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTables" xlink:type="extended" id="ie1852e7fd8a04c83a1ec266f37978939_StockBasedCompensationTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationDetails" xlink:type="extended" id="idcbad609faad460e812b5027b0c928c3_StockBasedCompensationDetails"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockAwardsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationRestrictedStockAwardsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockAwardsDetails" xlink:type="extended" id="ic4337096ed0648d2919f044f99cab4b7_StockBasedCompensationRestrictedStockAwardsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_4aac5440-347a-4b9f-a703-820ef634fad9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_4aac5440-347a-4b9f-a703-820ef634fad9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_60dcba8c-c8dd-455b-905a-2444b149c54a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_60dcba8c-c8dd-455b-905a-2444b149c54a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f654778f-a72f-4dfa-b481-c84dd86eccfb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_60dcba8c-c8dd-455b-905a-2444b149c54a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f654778f-a72f-4dfa-b481-c84dd86eccfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_eda429ab-49c7-4919-9022-39023153ef59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_60dcba8c-c8dd-455b-905a-2444b149c54a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_eda429ab-49c7-4919-9022-39023153ef59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_d66df9d6-2eb2-43a1-981c-67870b233ef8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_60dcba8c-c8dd-455b-905a-2444b149c54a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_d66df9d6-2eb2-43a1-981c-67870b233ef8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_09513012-7b6c-4948-bd50-9fb571974979" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_60dcba8c-c8dd-455b-905a-2444b149c54a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_09513012-7b6c-4948-bd50-9fb571974979" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d1c03962-1275-4ae9-8a55-451e379a64e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_485c7235-c006-4912-a9c7-52ba8dc18fb9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_485c7235-c006-4912-a9c7-52ba8dc18fb9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_cefaccd1-1731-4f6a-9886-8c5e6c438193" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_485c7235-c006-4912-a9c7-52ba8dc18fb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_cefaccd1-1731-4f6a-9886-8c5e6c438193" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_d88243f6-1661-4ef5-86e0-b7a0723f158e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_485c7235-c006-4912-a9c7-52ba8dc18fb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_d88243f6-1661-4ef5-86e0-b7a0723f158e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_4885571d-6f37-4b2d-8085-3f73d621ea50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_485c7235-c006-4912-a9c7-52ba8dc18fb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_4885571d-6f37-4b2d-8085-3f73d621ea50" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_c34e0a56-d215-4fca-8102-ba075ee84980" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_485c7235-c006-4912-a9c7-52ba8dc18fb9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_c34e0a56-d215-4fca-8102-ba075ee84980" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_a55a3327-f3d3-466c-974c-e8063eea68e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_5372721e-be65-4b9d-b062-901a07d19358" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_5372721e-be65-4b9d-b062-901a07d19358" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_fe906139-311e-46a6-85f3-20de757f17c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_fe906139-311e-46a6-85f3-20de757f17c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_62952e53-dce9-4303-bc39-2cc9c3b61f49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_62952e53-dce9-4303-bc39-2cc9c3b61f49" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_de957ecb-e3df-4bc5-911d-f073409808d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c1a55cd4-4159-4be3-ab81-0928113036d1" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_de957ecb-e3df-4bc5-911d-f073409808d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_fe9749cd-dcdb-40e4-a0fa-214f39880d32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_de957ecb-e3df-4bc5-911d-f073409808d8" xlink:to="loc_us-gaap_AwardTypeAxis_fe9749cd-dcdb-40e4-a0fa-214f39880d32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fe9749cd-dcdb-40e4-a0fa-214f39880d32_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_fe9749cd-dcdb-40e4-a0fa-214f39880d32" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fe9749cd-dcdb-40e4-a0fa-214f39880d32_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bc0a45f9-93ea-4766-83e3-49a6ea085ed4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_fe9749cd-dcdb-40e4-a0fa-214f39880d32" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bc0a45f9-93ea-4766-83e3-49a6ea085ed4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_cb5de3cd-b4e1-46b9-a489-807222effdc6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bc0a45f9-93ea-4766-83e3-49a6ea085ed4" xlink:to="loc_us-gaap_RestrictedStockMember_cb5de3cd-b4e1-46b9-a489-807222effdc6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationStockOptionsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationStockOptionsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationStockOptionsDetails" xlink:type="extended" id="i11db7d497a964c15ab5c9e1bd99b2227_StockBasedCompensationStockOptionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e95c984-f50f-4be3-93c1-23f4cd80fa16" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_5a85a45a-c3b4-4f80-81e5-9378d8f8eefc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e95c984-f50f-4be3-93c1-23f4cd80fa16" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_5a85a45a-c3b4-4f80-81e5-9378d8f8eefc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_8b038c12-b0f6-42c1-9caa-82f19904ed4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e95c984-f50f-4be3-93c1-23f4cd80fa16" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_8b038c12-b0f6-42c1-9caa-82f19904ed4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_f97aa261-db60-4304-a488-a0f810273b83" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e95c984-f50f-4be3-93c1-23f4cd80fa16" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_f97aa261-db60-4304-a488-a0f810273b83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4edc73cf-5892-4861-a82b-f1d537b032bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1e95c984-f50f-4be3-93c1-23f4cd80fa16" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4edc73cf-5892-4861-a82b-f1d537b032bd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_897a3637-f9a9-4e3d-8d69-215b857b1da0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4edc73cf-5892-4861-a82b-f1d537b032bd" xlink:to="loc_us-gaap_AwardTypeAxis_897a3637-f9a9-4e3d-8d69-215b857b1da0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_897a3637-f9a9-4e3d-8d69-215b857b1da0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_897a3637-f9a9-4e3d-8d69-215b857b1da0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_897a3637-f9a9-4e3d-8d69-215b857b1da0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_59cda1a0-d1c9-4284-aa6c-f3de28cabacd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_897a3637-f9a9-4e3d-8d69-215b857b1da0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_59cda1a0-d1c9-4284-aa6c-f3de28cabacd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_50507544-ede2-499a-8afa-8a4934e6c69b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_59cda1a0-d1c9-4284-aa6c-f3de28cabacd" xlink:to="loc_us-gaap_EmployeeStockOptionMember_50507544-ede2-499a-8afa-8a4934e6c69b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationRestrictedStockUnitsDetails" xlink:type="extended" id="ia273682bb5a14f8e87a8c298a0b72547_StockBasedCompensationRestrictedStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_6402b9d2-4750-4431-9719-c91b9834022d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_6402b9d2-4750-4431-9719-c91b9834022d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0252aa52-f343-42de-9cd8-dbd098c4e2c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0252aa52-f343-42de-9cd8-dbd098c4e2c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_aed9177a-fffe-4ded-b0c2-2ebbe575dce2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_aed9177a-fffe-4ded-b0c2-2ebbe575dce2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c1e91d07-f8db-4b2e-8c6b-f67d79e8ff3e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c1e91d07-f8db-4b2e-8c6b-f67d79e8ff3e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_07e6235d-5d79-4715-9062-9f860780eeac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_07e6235d-5d79-4715-9062-9f860780eeac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardCashPaidToSettleVestedInstruments_b540200a-c5c6-4429-a357-61943b59446a" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardCashPaidToSettleVestedInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_nx_ShareBasedCompensationArrangementByShareBasedPaymentAwardCashPaidToSettleVestedInstruments_b540200a-c5c6-4429-a357-61943b59446a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c9b4db6c-d38d-41e1-8743-3c546921f080" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_65953a95-ae6b-45d9-850c-70ed04dfcda8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c9b4db6c-d38d-41e1-8743-3c546921f080" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_235321a2-679e-432a-8886-9fe59b06c19d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c9b4db6c-d38d-41e1-8743-3c546921f080" xlink:to="loc_us-gaap_AwardTypeAxis_235321a2-679e-432a-8886-9fe59b06c19d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_235321a2-679e-432a-8886-9fe59b06c19d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_235321a2-679e-432a-8886-9fe59b06c19d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_235321a2-679e-432a-8886-9fe59b06c19d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_81eb885f-69b0-49c4-b3e4-8830e1cc1a8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_235321a2-679e-432a-8886-9fe59b06c19d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_81eb885f-69b0-49c4-b3e4-8830e1cc1a8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_39521696-017e-4ff1-a971-63a8b8955da3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_81eb885f-69b0-49c4-b3e4-8830e1cc1a8d" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_39521696-017e-4ff1-a971-63a8b8955da3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceShareAwardsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationPerformanceShareAwardsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceShareAwardsDetails" xlink:type="extended" id="ie13cfe5cd6e04eb19592adc2bd2756fa_StockBasedCompensationPerformanceShareAwardsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_PerformanceSharesSettledinCash_5578c4fe-dbe1-4609-aaea-2753663766e4" xlink:href="nx-20210131.xsd#nx_PerformanceSharesSettledinCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_nx_PerformanceSharesSettledinCash_5578c4fe-dbe1-4609-aaea-2753663766e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_736b6270-2e84-4031-8fa7-bfeca15ca998" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_736b6270-2e84-4031-8fa7-bfeca15ca998" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_66c5314a-6d70-4cfa-a390-93efee6d0562" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_66c5314a-6d70-4cfa-a390-93efee6d0562" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ReturnOnNetAssets_95848090-53f1-4a6c-981b-1c7db56084e3" xlink:href="nx-20210131.xsd#nx_ReturnOnNetAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_nx_ReturnOnNetAssets_95848090-53f1-4a6c-981b-1c7db56084e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_8fe75230-9596-4b13-acbc-998038edcdf9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_8fe75230-9596-4b13-acbc-998038edcdf9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_6277790a-cbb3-4814-842e-1d2411677e8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_6277790a-cbb3-4814-842e-1d2411677e8a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_4bcdb164-bee7-434a-a04f-d477645e2391" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_4bcdb164-bee7-434a-a04f-d477645e2391" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_52fe9ae0-4c11-4000-96f4-ca50256f3d99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4714cfb-9b50-4b02-a6bc-0f7f69775655" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_52fe9ae0-4c11-4000-96f4-ca50256f3d99" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_dcef4a57-067a-4d64-b73a-f47b43642812" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_52fe9ae0-4c11-4000-96f4-ca50256f3d99" xlink:to="loc_us-gaap_AwardTypeAxis_dcef4a57-067a-4d64-b73a-f47b43642812" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dcef4a57-067a-4d64-b73a-f47b43642812_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_dcef4a57-067a-4d64-b73a-f47b43642812" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dcef4a57-067a-4d64-b73a-f47b43642812_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e59181ae-8429-4701-82c6-14010fa9e735" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_dcef4a57-067a-4d64-b73a-f47b43642812" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e59181ae-8429-4701-82c6-14010fa9e735" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_dfa980d8-b1e9-470a-8ba9-d3af52de47d6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e59181ae-8429-4701-82c6-14010fa9e735" xlink:to="loc_us-gaap_PerformanceSharesMember_dfa980d8-b1e9-470a-8ba9-d3af52de47d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_bdb79f33-0bcc-4261-b19c-05138bb58bfa" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_52fe9ae0-4c11-4000-96f4-ca50256f3d99" xlink:to="loc_srt_RangeAxis_bdb79f33-0bcc-4261-b19c-05138bb58bfa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_bdb79f33-0bcc-4261-b19c-05138bb58bfa_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_bdb79f33-0bcc-4261-b19c-05138bb58bfa" xlink:to="loc_srt_RangeMember_bdb79f33-0bcc-4261-b19c-05138bb58bfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_da634cb8-c71b-478d-97f3-e891180a47b1" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_bdb79f33-0bcc-4261-b19c-05138bb58bfa" xlink:to="loc_srt_RangeMember_da634cb8-c71b-478d-97f3-e891180a47b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_35f664f2-9ca3-4e4e-bc6e-e59ac86575a2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_da634cb8-c71b-478d-97f3-e891180a47b1" xlink:to="loc_srt_MinimumMember_35f664f2-9ca3-4e4e-bc6e-e59ac86575a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1bad0d31-9787-4651-bb82-ccca038600d5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_da634cb8-c71b-478d-97f3-e891180a47b1" xlink:to="loc_srt_MaximumMember_1bad0d31-9787-4651-bb82-ccca038600d5" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationPerformanceRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationPerformanceRestrictedStockUnitsDetails" xlink:type="extended" id="idb8391b416cd48e8b77ae5c0a727feab_StockBasedCompensationPerformanceRestrictedStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_455c35e7-7a39-49bd-b305-e746e759030b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_455c35e7-7a39-49bd-b305-e746e759030b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_e56b82e9-3b58-4944-8fbf-4f2298458605" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_e56b82e9-3b58-4944-8fbf-4f2298458605" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_00f3d978-746b-4031-a895-3928fc7afdf4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_00f3d978-746b-4031-a895-3928fc7afdf4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_a0d59ef3-a405-413a-a5fc-85563014a3bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_a0d59ef3-a405-413a-a5fc-85563014a3bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_40e745da-920e-46cb-b620-86b38afbbf14" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_40e745da-920e-46cb-b620-86b38afbbf14" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_353d3cb1-e7b3-4cb6-860f-a1f384cb57e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_353d3cb1-e7b3-4cb6-860f-a1f384cb57e6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_901fd022-f3f2-413e-8014-deb1a97c5865" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_901fd022-f3f2-413e-8014-deb1a97c5865" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5762ea91-e0d4-4772-8c03-ce32ad7673a1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_3d145d3f-7b34-4971-8beb-cea8363becf3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5762ea91-e0d4-4772-8c03-ce32ad7673a1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_ff30a75d-6e43-4e26-b649-91b11770c89b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5762ea91-e0d4-4772-8c03-ce32ad7673a1" xlink:to="loc_us-gaap_AwardTypeAxis_ff30a75d-6e43-4e26-b649-91b11770c89b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ff30a75d-6e43-4e26-b649-91b11770c89b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_ff30a75d-6e43-4e26-b649-91b11770c89b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ff30a75d-6e43-4e26-b649-91b11770c89b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_66bd920c-2df9-4165-8440-39ed5be23d52" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_ff30a75d-6e43-4e26-b649-91b11770c89b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_66bd920c-2df9-4165-8440-39ed5be23d52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_PerformanceRestrictedStockUnitsMember_11d4dd97-3af3-4efb-acb6-ceb88e35f5e8" xlink:href="nx-20210131.xsd#nx_PerformanceRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_66bd920c-2df9-4165-8440-39ed5be23d52" xlink:to="loc_nx_PerformanceRestrictedStockUnitsMember_11d4dd97-3af3-4efb-acb6-ceb88e35f5e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_5accfbf3-3d0d-44a5-86bf-8476d2093f5d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5762ea91-e0d4-4772-8c03-ce32ad7673a1" xlink:to="loc_srt_RangeAxis_5accfbf3-3d0d-44a5-86bf-8476d2093f5d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5accfbf3-3d0d-44a5-86bf-8476d2093f5d_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_5accfbf3-3d0d-44a5-86bf-8476d2093f5d" xlink:to="loc_srt_RangeMember_5accfbf3-3d0d-44a5-86bf-8476d2093f5d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_59347ff9-4b4a-4541-aea6-a8d79b5b8286" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_5accfbf3-3d0d-44a5-86bf-8476d2093f5d" xlink:to="loc_srt_RangeMember_59347ff9-4b4a-4541-aea6-a8d79b5b8286" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_d5a6b48e-b02f-4f8d-a7aa-162b439cf2b2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_59347ff9-4b4a-4541-aea6-a8d79b5b8286" xlink:to="loc_srt_MinimumMember_d5a6b48e-b02f-4f8d-a7aa-162b439cf2b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_6e4486eb-b88e-4dd9-bc66-7b786684d6a3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_59347ff9-4b4a-4541-aea6-a8d79b5b8286" xlink:to="loc_srt_MaximumMember_6e4486eb-b88e-4dd9-bc66-7b786684d6a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_8539216c-9e77-4f0f-a7ca-029e520d3f48" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5762ea91-e0d4-4772-8c03-ce32ad7673a1" xlink:to="loc_us-gaap_VestingAxis_8539216c-9e77-4f0f-a7ca-029e520d3f48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_8539216c-9e77-4f0f-a7ca-029e520d3f48_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_8539216c-9e77-4f0f-a7ca-029e520d3f48" xlink:to="loc_us-gaap_VestingDomain_8539216c-9e77-4f0f-a7ca-029e520d3f48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_c5fe6296-c15b-439b-8d08-fd3bbe46a3db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_8539216c-9e77-4f0f-a7ca-029e520d3f48" xlink:to="loc_us-gaap_VestingDomain_c5fe6296-c15b-439b-8d08-fd3bbe46a3db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_e7c787f8-3913-45a1-af36-23775ef5da90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c5fe6296-c15b-439b-8d08-fd3bbe46a3db" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_e7c787f8-3913-45a1-af36-23775ef5da90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_4d7a74b5-d9cf-4a70-80d0-630e5199b35f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c5fe6296-c15b-439b-8d08-fd3bbe46a3db" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_4d7a74b5-d9cf-4a70-80d0-630e5199b35f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_6e4561ab-9c6e-4af8-b236-7f8833e240f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c5fe6296-c15b-439b-8d08-fd3bbe46a3db" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_6e4561ab-9c6e-4af8-b236-7f8833e240f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardTrancheFourMember_9dd8d0fe-e5d4-4bcd-b16d-b324c38e8573" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardTrancheFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_c5fe6296-c15b-439b-8d08-fd3bbe46a3db" xlink:to="loc_nx_ShareBasedCompensationAwardTrancheFourMember_9dd8d0fe-e5d4-4bcd-b16d-b324c38e8573" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_b41f8486-f41c-49cf-8a9a-690f12d66a06" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_5762ea91-e0d4-4772-8c03-ce32ad7673a1" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_b41f8486-f41c-49cf-8a9a-690f12d66a06" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_b41f8486-f41c-49cf-8a9a-690f12d66a06_default" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_b41f8486-f41c-49cf-8a9a-690f12d66a06" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_b41f8486-f41c-49cf-8a9a-690f12d66a06_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_34e7d5dd-5972-4701-abcf-b557e4f1766d" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAxis_b41f8486-f41c-49cf-8a9a-690f12d66a06" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_34e7d5dd-5972-4701-abcf-b557e4f1766d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesGreaterThanOrEqualTo50PercentMember_c0b18813-19aa-4bb6-ab9b-6feceb79555b" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesGreaterThanOrEqualTo50PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_34e7d5dd-5972-4701-abcf-b557e4f1766d" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesGreaterThanOrEqualTo50PercentMember_c0b18813-19aa-4bb6-ab9b-6feceb79555b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan50PercentAndGreaterThanOrEqualTo20PercentMember_17587630-8c72-497a-9b6d-34779f403690" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan50PercentAndGreaterThanOrEqualTo20PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_34e7d5dd-5972-4701-abcf-b557e4f1766d" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan50PercentAndGreaterThanOrEqualTo20PercentMember_17587630-8c72-497a-9b6d-34779f403690" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan20PercentAndGreaterThanOrEqualToNegative20PercentMember_669393f5-1c0d-49f3-af51-66e4a0be1dc0" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan20PercentAndGreaterThanOrEqualToNegative20PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_34e7d5dd-5972-4701-abcf-b557e4f1766d" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThan20PercentAndGreaterThanOrEqualToNegative20PercentMember_669393f5-1c0d-49f3-af51-66e4a0be1dc0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThanNegative20PercentMember_4d8ad2a4-8b31-4628-a30d-ade197e5ed4b" xlink:href="nx-20210131.xsd#nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThanNegative20PercentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaDomain_34e7d5dd-5972-4701-abcf-b557e4f1766d" xlink:to="loc_nx_ShareBasedCompensationAwardPerformanceCriteriaAbsoluteTotalShareholderReturnMilestonesLessThanNegative20PercentMember_4d8ad2a4-8b31-4628-a30d-ade197e5ed4b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTreasurySharesDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#StockBasedCompensationTreasurySharesDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/StockBasedCompensationTreasurySharesDetails" xlink:type="extended" id="i88d5b48ce3cf415c83f3c97bf3a9abd8_StockBasedCompensationTreasurySharesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e4d0a9a6-30c5-4e55-8954-303c2cbe415d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_f92c7280-cbc5-471e-8d6e-50fef1bcdc49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e4d0a9a6-30c5-4e55-8954-303c2cbe415d" xlink:to="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_f92c7280-cbc5-471e-8d6e-50fef1bcdc49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockShares_e29cb040-f629-476f-86c4-8f57c72b4071" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_f92c7280-cbc5-471e-8d6e-50fef1bcdc49" xlink:to="loc_us-gaap_TreasuryStockShares_e29cb040-f629-476f-86c4-8f57c72b4071" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_f9413fcb-b22c-4bdf-b357-34ab06c1bc81" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_f92c7280-cbc5-471e-8d6e-50fef1bcdc49" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_f9413fcb-b22c-4bdf-b357-34ab06c1bc81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_34edfbd1-5225-4264-afac-a1476835a743" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_f92c7280-cbc5-471e-8d6e-50fef1bcdc49" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_34edfbd1-5225-4264-afac-a1476835a743" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_c31990c8-4a8b-46cc-b957-721cff8994fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TreasuryStockNumberOfSharesAndRestrictionDisclosuresAbstract_f92c7280-cbc5-471e-8d6e-50fef1bcdc49" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_c31990c8-4a8b-46cc-b957-721cff8994fe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockShares_a6d790e1-4548-459e-a9d4-45bbeb805f6f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e589edcc-28bf-40d1-98ef-c0af361f2ba5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e4d0a9a6-30c5-4e55-8954-303c2cbe415d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e589edcc-28bf-40d1-98ef-c0af361f2ba5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_8d9358fc-e2b0-403b-bfc7-842102ed0f59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e589edcc-28bf-40d1-98ef-c0af361f2ba5" xlink:to="loc_us-gaap_AwardTypeAxis_8d9358fc-e2b0-403b-bfc7-842102ed0f59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8d9358fc-e2b0-403b-bfc7-842102ed0f59_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8d9358fc-e2b0-403b-bfc7-842102ed0f59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8d9358fc-e2b0-403b-bfc7-842102ed0f59_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3f74aa6b-65b6-4aa7-baec-d785fca1d4fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8d9358fc-e2b0-403b-bfc7-842102ed0f59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3f74aa6b-65b6-4aa7-baec-d785fca1d4fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_c1f89ee2-4e1b-48a4-ae4a-6075085591af" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3f74aa6b-65b6-4aa7-baec-d785fca1d4fd" xlink:to="loc_us-gaap_RestrictedStockMember_c1f89ee2-4e1b-48a4-ae4a-6075085591af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_bdc36865-ddc8-47e5-96c3-e29a4424e625" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3f74aa6b-65b6-4aa7-baec-d785fca1d4fd" xlink:to="loc_us-gaap_PerformanceSharesMember_bdc36865-ddc8-47e5-96c3-e29a4424e625" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_f98e3a03-9710-46c9-b64d-33eb84be992a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3f74aa6b-65b6-4aa7-baec-d785fca1d4fd" xlink:to="loc_us-gaap_EmployeeStockOptionMember_f98e3a03-9710-46c9-b64d-33eb84be992a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/OtherIncome" xlink:type="simple" xlink:href="nx-20210131.xsd#OtherIncome"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/OtherIncome" xlink:type="extended" id="i19911df4d4d34254b818e46738b86589_OtherIncome"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseTables" xlink:type="simple" xlink:href="nx-20210131.xsd#OtherIncomeExpenseTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseTables" xlink:type="extended" id="i98673f80b5954d10a8f28511f337bd55_OtherIncomeExpenseTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseDetail" xlink:type="simple" xlink:href="nx-20210131.xsd#OtherIncomeExpenseDetail"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/OtherIncomeExpenseDetail" xlink:type="extended" id="i8ff3247ae0074f08abcb529a3864a921_OtherIncomeExpenseDetail"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationNotes" xlink:type="simple" xlink:href="nx-20210131.xsd#SegmentInformationNotes"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationNotes" xlink:type="extended" id="i580dc3c1574a4b20ad7dc86d09ea7a1a_SegmentInformationNotes"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationTables" xlink:type="simple" xlink:href="nx-20210131.xsd#SegmentInformationTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationTables" xlink:type="extended" id="if5e6900897de4aba9c5362e8aa9df3a2_SegmentInformationTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#SegmentInformationDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationDetails" xlink:type="extended" id="i75fee811bc6643a8abec6a75e38e4262_SegmentInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_6ea26dad-e9e2-4e35-a643-db03d735dc58" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_c43451d3-d16c-446e-9abd-37238f7fa31d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6ea26dad-e9e2-4e35-a643-db03d735dc58" xlink:to="loc_us-gaap_NumberOfReportableSegments_c43451d3-d16c-446e-9abd-37238f7fa31d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_7370cfa3-4e0d-4a7a-92d1-38472818cbba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6ea26dad-e9e2-4e35-a643-db03d735dc58" xlink:to="loc_us-gaap_NumberOfOperatingSegments_7370cfa3-4e0d-4a7a-92d1-38472818cbba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_4d17c992-0141-4c96-b6b6-51c3fca4244f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6ea26dad-e9e2-4e35-a643-db03d735dc58" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_4d17c992-0141-4c96-b6b6-51c3fca4244f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6a8db7c9-887f-4c59-a2ab-cebc9adcaace" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_6ea26dad-e9e2-4e35-a643-db03d735dc58" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6a8db7c9-887f-4c59-a2ab-cebc9adcaace" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_ad721dd9-6b32-498b-bb55-8f2fad8094ac" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6a8db7c9-887f-4c59-a2ab-cebc9adcaace" xlink:to="loc_srt_ConsolidationItemsAxis_ad721dd9-6b32-498b-bb55-8f2fad8094ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ad721dd9-6b32-498b-bb55-8f2fad8094ac_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_ad721dd9-6b32-498b-bb55-8f2fad8094ac" xlink:to="loc_srt_ConsolidationItemsDomain_ad721dd9-6b32-498b-bb55-8f2fad8094ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_0372340e-2713-4b96-97f3-788049be03a9" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_ad721dd9-6b32-498b-bb55-8f2fad8094ac" xlink:to="loc_srt_ConsolidationItemsDomain_0372340e-2713-4b96-97f3-788049be03a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_176052f1-425d-49b5-ac98-5c6a9d508007" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_0372340e-2713-4b96-97f3-788049be03a9" xlink:to="loc_us-gaap_OperatingSegmentsMember_176052f1-425d-49b5-ac98-5c6a9d508007" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_653aa36a-a584-4178-aa11-c5c855948aac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_0372340e-2713-4b96-97f3-788049be03a9" xlink:to="loc_us-gaap_CorporateNonSegmentMember_653aa36a-a584-4178-aa11-c5c855948aac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_413558e8-b42e-4abb-8ae1-1c63129fa422" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6a8db7c9-887f-4c59-a2ab-cebc9adcaace" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_413558e8-b42e-4abb-8ae1-1c63129fa422" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_413558e8-b42e-4abb-8ae1-1c63129fa422_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_413558e8-b42e-4abb-8ae1-1c63129fa422" xlink:to="loc_us-gaap_SegmentDomain_413558e8-b42e-4abb-8ae1-1c63129fa422_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_2009a297-89e9-466d-a1d8-3e1b983db913" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_413558e8-b42e-4abb-8ae1-1c63129fa422" xlink:to="loc_us-gaap_SegmentDomain_2009a297-89e9-466d-a1d8-3e1b983db913" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NAEngineeredComponentsMember_67e67250-4c74-4817-b66e-6e109d106f7f" xlink:href="nx-20210131.xsd#nx_NAEngineeredComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2009a297-89e9-466d-a1d8-3e1b983db913" xlink:to="loc_nx_NAEngineeredComponentsMember_67e67250-4c74-4817-b66e-6e109d106f7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_EUEngineeredComponentsMember_059b7d96-f020-4872-982e-d0b28122eb4a" xlink:href="nx-20210131.xsd#nx_EUEngineeredComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2009a297-89e9-466d-a1d8-3e1b983db913" xlink:to="loc_nx_EUEngineeredComponentsMember_059b7d96-f020-4872-982e-d0b28122eb4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NACabinetComponentsMember_66fc2654-7c55-4d9f-aa98-a0b487eb3fa1" xlink:href="nx-20210131.xsd#nx_NACabinetComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2009a297-89e9-466d-a1d8-3e1b983db913" xlink:to="loc_nx_NACabinetComponentsMember_66fc2654-7c55-4d9f-aa98-a0b487eb3fa1" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationSegmentReportingInformationDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#SegmentInformationSegmentReportingInformationDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationSegmentReportingInformationDetails" xlink:type="extended" id="iaf51340e60764a96aed4e1510bb27290_SegmentInformationSegmentReportingInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_dfd085a1-24d3-4a54-b4ea-882d99315c1a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_dfd085a1-24d3-4a54-b4ea-882d99315c1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_a2247648-1b93-45b4-b9cf-dec1b1443678" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_a2247648-1b93-45b4-b9cf-dec1b1443678" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_5709b15d-4c02-46f1-bc5c-bed137d25062" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_5709b15d-4c02-46f1-bc5c-bed137d25062" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_4eb6025b-f097-4de2-9c42-779cbb874995" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_OperatingIncomeLoss_4eb6025b-f097-4de2-9c42-779cbb874995" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_9d9f1834-32ed-4f45-b781-e6e9b1e6b1a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_9d9f1834-32ed-4f45-b781-e6e9b1e6b1a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_ddd66c92-ea86-428c-af0f-560b44b8ab11" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_Assets_ddd66c92-ea86-428c-af0f-560b44b8ab11" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_99e5559f-6c06-4b12-8130-81f67dc374a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_18eb1dcd-952a-447e-b2ec-3216fce1ef97" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_99e5559f-6c06-4b12-8130-81f67dc374a0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_841ae029-7e34-4a0b-bf29-53bc12534ec1" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_99e5559f-6c06-4b12-8130-81f67dc374a0" xlink:to="loc_srt_ConsolidationItemsAxis_841ae029-7e34-4a0b-bf29-53bc12534ec1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_841ae029-7e34-4a0b-bf29-53bc12534ec1_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_841ae029-7e34-4a0b-bf29-53bc12534ec1" xlink:to="loc_srt_ConsolidationItemsDomain_841ae029-7e34-4a0b-bf29-53bc12534ec1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_67b95671-6ea9-4f29-8ddc-e3d3660917db" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_841ae029-7e34-4a0b-bf29-53bc12534ec1" xlink:to="loc_srt_ConsolidationItemsDomain_67b95671-6ea9-4f29-8ddc-e3d3660917db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_d78c0a5b-f7dc-4091-bf5d-9d2e860db1c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_67b95671-6ea9-4f29-8ddc-e3d3660917db" xlink:to="loc_us-gaap_OperatingSegmentsMember_d78c0a5b-f7dc-4091-bf5d-9d2e860db1c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_20eda100-1154-4942-955d-dfa5e12e490c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_67b95671-6ea9-4f29-8ddc-e3d3660917db" xlink:to="loc_us-gaap_CorporateNonSegmentMember_20eda100-1154-4942-955d-dfa5e12e490c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_4af72434-5cb8-4670-bc06-98333bfb6c08" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_99e5559f-6c06-4b12-8130-81f67dc374a0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_4af72434-5cb8-4670-bc06-98333bfb6c08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4af72434-5cb8-4670-bc06-98333bfb6c08_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_4af72434-5cb8-4670-bc06-98333bfb6c08" xlink:to="loc_us-gaap_SegmentDomain_4af72434-5cb8-4670-bc06-98333bfb6c08_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_408edfa9-37cc-4b75-ade2-a4189047270c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_4af72434-5cb8-4670-bc06-98333bfb6c08" xlink:to="loc_us-gaap_SegmentDomain_408edfa9-37cc-4b75-ade2-a4189047270c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NAFenestrationMember_80ce4256-bb33-4144-bf25-95e775190669" xlink:href="nx-20210131.xsd#nx_NAFenestrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_408edfa9-37cc-4b75-ade2-a4189047270c" xlink:to="loc_nx_NAFenestrationMember_80ce4256-bb33-4144-bf25-95e775190669" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_EUFenestrationMember_4c2bcba8-c2b1-469d-a36f-80728873fd27" xlink:href="nx-20210131.xsd#nx_EUFenestrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_408edfa9-37cc-4b75-ade2-a4189047270c" xlink:to="loc_nx_EUFenestrationMember_4c2bcba8-c2b1-469d-a36f-80728873fd27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NACabinetComponentsMember_8b229e60-18a4-4344-bd12-43f2d83ef27b" xlink:href="nx-20210131.xsd#nx_NACabinetComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_408edfa9-37cc-4b75-ade2-a4189047270c" xlink:to="loc_nx_NACabinetComponentsMember_8b229e60-18a4-4344-bd12-43f2d83ef27b" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationGoodwillbySegmentDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#SegmentInformationGoodwillbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationGoodwillbySegmentDetails" xlink:type="extended" id="i3a6eb07ccaa04abca8f55de307cec739_SegmentInformationGoodwillbySegmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_772fdcaf-f6a3-4cfc-817b-e12d5bf49536" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_09cc18ca-8eb7-4422-9ce9-0d5cef2d7716" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_772fdcaf-f6a3-4cfc-817b-e12d5bf49536" xlink:to="loc_us-gaap_Goodwill_09cc18ca-8eb7-4422-9ce9-0d5cef2d7716" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_7ab052ee-bb37-497e-91aa-f6128a872de4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_772fdcaf-f6a3-4cfc-817b-e12d5bf49536" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_7ab052ee-bb37-497e-91aa-f6128a872de4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_495ae54d-5019-4b5b-87dc-e4e94a69e674" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_6366fef5-b64c-402b-9b9b-89e6726ef2a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_772fdcaf-f6a3-4cfc-817b-e12d5bf49536" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_6366fef5-b64c-402b-9b9b-89e6726ef2a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_b6a3c736-6d4b-4a34-aa61-ff778e05882e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_6366fef5-b64c-402b-9b9b-89e6726ef2a6" xlink:to="loc_srt_ConsolidationItemsAxis_b6a3c736-6d4b-4a34-aa61-ff778e05882e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_b6a3c736-6d4b-4a34-aa61-ff778e05882e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_b6a3c736-6d4b-4a34-aa61-ff778e05882e" xlink:to="loc_srt_ConsolidationItemsDomain_b6a3c736-6d4b-4a34-aa61-ff778e05882e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ed3c4334-aa28-46e4-8085-32d2760ea5a0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_b6a3c736-6d4b-4a34-aa61-ff778e05882e" xlink:to="loc_srt_ConsolidationItemsDomain_ed3c4334-aa28-46e4-8085-32d2760ea5a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_79652bf2-c71f-48f3-9510-8ebed9f89c74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ed3c4334-aa28-46e4-8085-32d2760ea5a0" xlink:to="loc_us-gaap_OperatingSegmentsMember_79652bf2-c71f-48f3-9510-8ebed9f89c74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_36bf2a09-332f-4cae-a16b-5c9011835009" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ed3c4334-aa28-46e4-8085-32d2760ea5a0" xlink:to="loc_us-gaap_CorporateNonSegmentMember_36bf2a09-332f-4cae-a16b-5c9011835009" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_000e75b0-9e91-4fc6-b8de-e9e4a2245fc7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_6366fef5-b64c-402b-9b9b-89e6726ef2a6" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_000e75b0-9e91-4fc6-b8de-e9e4a2245fc7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_000e75b0-9e91-4fc6-b8de-e9e4a2245fc7_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_000e75b0-9e91-4fc6-b8de-e9e4a2245fc7" xlink:to="loc_us-gaap_SegmentDomain_000e75b0-9e91-4fc6-b8de-e9e4a2245fc7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_60ba1020-799a-454e-ac9e-a37172ee1064" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_000e75b0-9e91-4fc6-b8de-e9e4a2245fc7" xlink:to="loc_us-gaap_SegmentDomain_60ba1020-799a-454e-ac9e-a37172ee1064" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NAEngineeredComponentsMember_f662ec36-c4b9-403b-842a-26badad667c7" xlink:href="nx-20210131.xsd#nx_NAEngineeredComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_60ba1020-799a-454e-ac9e-a37172ee1064" xlink:to="loc_nx_NAEngineeredComponentsMember_f662ec36-c4b9-403b-842a-26badad667c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_EUEngineeredComponentsMember_e25e45a0-31c0-49b8-931d-aab9f5e7c095" xlink:href="nx-20210131.xsd#nx_EUEngineeredComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_60ba1020-799a-454e-ac9e-a37172ee1064" xlink:to="loc_nx_EUEngineeredComponentsMember_e25e45a0-31c0-49b8-931d-aab9f5e7c095" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_NACabinetComponentsMember_ee57a2a8-0ff8-416f-9775-6a6ce22fae51" xlink:href="nx-20210131.xsd#nx_NACabinetComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_60ba1020-799a-454e-ac9e-a37172ee1064" xlink:to="loc_nx_NACabinetComponentsMember_ee57a2a8-0ff8-416f-9775-6a6ce22fae51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_EUFenestrationMember_b7528b70-3aa4-4cf9-880b-3454c8333f1d" xlink:href="nx-20210131.xsd#nx_EUFenestrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_60ba1020-799a-454e-ac9e-a37172ee1064" xlink:to="loc_nx_EUFenestrationMember_b7528b70-3aa4-4cf9-880b-3454c8333f1d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/SegmentInformationReconcilliationofOperatingLosstoNetIncomeDetails" xlink:type="simple" xlink:href="nx-20210131.xsd#SegmentInformationReconcilliationofOperatingLosstoNetIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/SegmentInformationReconcilliationofOperatingLosstoNetIncomeDetails" xlink:type="extended" id="i79190db2ab794c4b8d1c8dc81d7a0965_SegmentInformationReconcilliationofOperatingLosstoNetIncomeDetails"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/EarningsPerShare" xlink:type="simple" xlink:href="nx-20210131.xsd#EarningsPerShare"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/EarningsPerShare" xlink:type="extended" id="i81b56ddc79ff41c0bac444c71b05eb2e_EarningsPerShare"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/EarningsPerShareEarningsPerShareTables" xlink:type="simple" xlink:href="nx-20210131.xsd#EarningsPerShareEarningsPerShareTables"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/EarningsPerShareEarningsPerShareTables" xlink:type="extended" id="i2e433746b7b44840ac6d542c4a989ae1_EarningsPerShareEarningsPerShareTables"/>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/EarningsPerShareDetail" xlink:type="simple" xlink:href="nx-20210131.xsd#EarningsPerShareDetail"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/EarningsPerShareDetail" xlink:type="extended" id="i32524dead8774172a6ff271e47bdb7af_EarningsPerShareDetail">
    <link:loc xlink:type="locator" xlink:label="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:href="nx-20210131.xsd#nx_EarningsPerShareDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_059f7c3a-cf7a-46c2-8582-2c0fd5d3e587" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_059f7c3a-cf7a-46c2-8582-2c0fd5d3e587" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_6ebbb26b-48f6-421b-abd1-7e56db69ed6a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_6ebbb26b-48f6-421b-abd1-7e56db69ed6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_ec97a53c-b027-42e4-a878-1142fc7db2fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_ec97a53c-b027-42e4-a878-1142fc7db2fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_e79edd5d-b5a9-4014-b310-9c39c2430159" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_e79edd5d-b5a9-4014-b310-9c39c2430159" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_0eec3abc-5a23-4a96-926b-a09ed291a1d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_0eec3abc-5a23-4a96-926b-a09ed291a1d7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_c7e75fe0-c1ad-4682-9b44-4a7910c3bb1b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_EarningsPerShareBasic_c7e75fe0-c1ad-4682-9b44-4a7910c3bb1b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_45d9061c-d2aa-4425-92b2-deeccd83b246" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_45d9061c-d2aa-4425-92b2-deeccd83b246" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_259a4b04-fb5f-4b84-bf88-3705c90b3bdb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_259a4b04-fb5f-4b84-bf88-3705c90b3bdb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_EarningsPerShareDisclosureTable_9ba9c71e-e5e3-4f0c-b798-ebd842977674" xlink:href="nx-20210131.xsd#nx_EarningsPerShareDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nx_EarningsPerShareDisclosureLineItems_230d404f-ee86-43bd-94f5-324f97e719fa" xlink:to="loc_nx_EarningsPerShareDisclosureTable_9ba9c71e-e5e3-4f0c-b798-ebd842977674" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_224e980c-6e38-43fb-890a-8761add15fa2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nx_EarningsPerShareDisclosureTable_9ba9c71e-e5e3-4f0c-b798-ebd842977674" xlink:to="loc_us-gaap_AwardTypeAxis_224e980c-6e38-43fb-890a-8761add15fa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_224e980c-6e38-43fb-890a-8761add15fa2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_224e980c-6e38-43fb-890a-8761add15fa2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_224e980c-6e38-43fb-890a-8761add15fa2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_62c8a264-0eb5-4a3a-b0be-6df9d4a052fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_224e980c-6e38-43fb-890a-8761add15fa2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_62c8a264-0eb5-4a3a-b0be-6df9d4a052fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_88917ed8-5da7-4dc3-9fb4-ee172cbce6fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_62c8a264-0eb5-4a3a-b0be-6df9d4a052fe" xlink:to="loc_us-gaap_EmployeeStockOptionMember_88917ed8-5da7-4dc3-9fb4-ee172cbce6fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_bb089b79-c505-406b-8799-e25f61d286ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_62c8a264-0eb5-4a3a-b0be-6df9d4a052fe" xlink:to="loc_us-gaap_RestrictedStockMember_bb089b79-c505-406b-8799-e25f61d286ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_5d021593-d256-412f-b49a-a44d5a9af5f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_62c8a264-0eb5-4a3a-b0be-6df9d4a052fe" xlink:to="loc_us-gaap_PerformanceSharesMember_5d021593-d256-412f-b49a-a44d5a9af5f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nx_PerformanceRestrictedStockUnitsMember_f6b4d1b7-b00a-4206-8eb9-3ad5be6cc400" xlink:href="nx-20210131.xsd#nx_PerformanceRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_62c8a264-0eb5-4a3a-b0be-6df9d4a052fe" xlink:to="loc_nx_PerformanceRestrictedStockUnitsMember_f6b4d1b7-b00a-4206-8eb9-3ad5be6cc400" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.quanexbuildingproducts.com/role/NewAccountingGuidance" xlink:type="simple" xlink:href="nx-20210131.xsd#NewAccountingGuidance"/>
  <link:definitionLink xlink:role="http://www.quanexbuildingproducts.com/role/NewAccountingGuidance" xlink:type="extended" id="i2d4a7cc5bd4a42838b450ccf27b95801_NewAccountingGuidance"/>
</link:linkbase>
