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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019ff6d2-46ce-71ae-8608-ecc228889f8a,g:4549dcae-98d8-4e60-b1fb-9869dd043aa1-->
<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://xbrl.sec.gov/oef/role/SeriesOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#SeriesOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/oef/role/SeriesOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_S000065204Member_019ff6d2-46ce-75e0-8c68-a1559a6978da" xlink:href="ck0001540305-20260826.xsd#ck0001540305_S000065204Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain" xlink:to="loc_ck0001540305_S000065204Member_019ff6d2-46ce-75e0-8c68-a1559a6978da" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ClassOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#ClassOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/oef/role/ClassOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_oef_ShareClassDomain" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_ShareClassDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_C000211051Member_019ff6d2-46ce-761c-bf95-6a35ac5a6034" xlink:href="ck0001540305-20260826.xsd#ck0001540305_C000211051Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_ShareClassDomain" xlink:to="loc_ck0001540305_C000211051Member_019ff6d2-46ce-761c-bf95-6a35ac5a6034" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/rr/role/RiskOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#RiskOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/rr/role/RiskOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_oef_AllRisksMember" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_AllRisksMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_EquityMarketRiskMember_019ff6d2-46ce-7671-b221-bcf37324b807" xlink:href="ck0001540305-20260826.xsd#ck0001540305_EquityMarketRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_EquityMarketRiskMember_019ff6d2-46ce-7671-b221-bcf37324b807" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ETFRisksMember_019ff6d2-46ce-7ba5-94a0-ad68b722c6a1" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ETFRisksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ETFRisksMember_019ff6d2-46ce-7ba5-94a0-ad68b722c6a1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ETFRisksAuthorizedParticipantsMarketMakersAndLiquidityProvidersConcentrationRiskMember_019ff6d2-46ce-7cef-8b9d-278a66b50ed7" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ETFRisksAuthorizedParticipantsMarketMakersAndLiquidityProvidersConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ETFRisksAuthorizedParticipantsMarketMakersAndLiquidityProvidersConcentrationRiskMember_019ff6d2-46ce-7cef-8b9d-278a66b50ed7" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ETFRisksCostsOfBuyingOrSellingSharesRiskMember_019ff6d2-46ce-7a4e-b667-4340b5b6d7f1" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ETFRisksCostsOfBuyingOrSellingSharesRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ETFRisksCostsOfBuyingOrSellingSharesRiskMember_019ff6d2-46ce-7a4e-b667-4340b5b6d7f1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ETFRisksSharesMayTradeAtPricesOtherThanNAVRiskMember_019ff6d2-46ce-7104-8d3f-6198df829962" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ETFRisksSharesMayTradeAtPricesOtherThanNAVRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ETFRisksSharesMayTradeAtPricesOtherThanNAVRiskMember_019ff6d2-46ce-7104-8d3f-6198df829962" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ETFRisksTradingRiskMember_019ff6d2-46ce-75a5-9c5f-4c4a3b78350b" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ETFRisksTradingRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ETFRisksTradingRiskMember_019ff6d2-46ce-75a5-9c5f-4c4a3b78350b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_HighPortfolioTurnoverRiskMember_019ff6d2-46ce-783a-a908-0792d52a6e9b" xlink:href="ck0001540305-20260826.xsd#ck0001540305_HighPortfolioTurnoverRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_HighPortfolioTurnoverRiskMember_019ff6d2-46ce-783a-a908-0792d52a6e9b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ManagementRiskMember_019ff6d2-46ce-754c-866f-d6d3a45022a4" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ManagementRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ManagementRiskMember_019ff6d2-46ce-754c-866f-d6d3a45022a4" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_MarketCapitalizationRiskMember_019ff6d2-46ce-7bb8-ab0e-1560b96c4440" xlink:href="ck0001540305-20260826.xsd#ck0001540305_MarketCapitalizationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_MarketCapitalizationRiskMember_019ff6d2-46ce-7bb8-ab0e-1560b96c4440" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_MarketCapitalizationRiskLargeCapitalizationInvestingRiskMember_019ff6d2-46ce-7e8c-8e47-c38a901deaa5" xlink:href="ck0001540305-20260826.xsd#ck0001540305_MarketCapitalizationRiskLargeCapitalizationInvestingRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_MarketCapitalizationRiskLargeCapitalizationInvestingRiskMember_019ff6d2-46ce-7e8c-8e47-c38a901deaa5" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_MarketCapitalizationRiskMidCapitalizationInvestingRiskMember_019ff6d2-46ce-73f9-b750-3cfe61163fb0" xlink:href="ck0001540305-20260826.xsd#ck0001540305_MarketCapitalizationRiskMidCapitalizationInvestingRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_MarketCapitalizationRiskMidCapitalizationInvestingRiskMember_019ff6d2-46ce-73f9-b750-3cfe61163fb0" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_ModelsAndDataRiskMember_019ff6d2-46ce-7a48-b08d-218a1af6b435" xlink:href="ck0001540305-20260826.xsd#ck0001540305_ModelsAndDataRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_ModelsAndDataRiskMember_019ff6d2-46ce-7a48-b08d-218a1af6b435" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_SectorRiskMember_019ff6d2-46ce-7e6b-9506-6c2fd43bbb0f" xlink:href="ck0001540305-20260826.xsd#ck0001540305_SectorRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_SectorRiskMember_019ff6d2-46ce-7e6b-9506-6c2fd43bbb0f" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_SectorRiskConsumerCyclicalSectorRiskMember_019ff6d2-46ce-7a2d-a768-e22bb729af3b" xlink:href="ck0001540305-20260826.xsd#ck0001540305_SectorRiskConsumerCyclicalSectorRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_SectorRiskConsumerCyclicalSectorRiskMember_019ff6d2-46ce-7a2d-a768-e22bb729af3b" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_SectorRiskEnergySectorRiskMember_019ff6d2-46ce-7588-9a3b-9f87cb596f39" xlink:href="ck0001540305-20260826.xsd#ck0001540305_SectorRiskEnergySectorRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_SectorRiskEnergySectorRiskMember_019ff6d2-46ce-7588-9a3b-9f87cb596f39" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_SectorRiskIndustrialsSectorRiskMember_019ff6d2-46ce-7587-97d9-e67e20e844e9" xlink:href="ck0001540305-20260826.xsd#ck0001540305_SectorRiskIndustrialsSectorRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_AllRisksMember" xlink:to="loc_ck0001540305_SectorRiskIndustrialsSectorRiskMember_019ff6d2-46ce-7587-97d9-e67e20e844e9" xlink:type="arc" order="24"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#PerformanceMeasureOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_oef_PerformanceMeasureDomain" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_PerformanceMeasureDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_ck0001540305_SP500TotalReturnIndexreflectsnodeductionforfeesexpensesortaxesIndexMember_019ff6d2-46ce-7ea8-b8fb-8a7c4d713267" xlink:href="ck0001540305-20260826.xsd#ck0001540305_SP500TotalReturnIndexreflectsnodeductionforfeesexpensesortaxesIndexMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oef_PerformanceMeasureDomain" xlink:to="loc_ck0001540305_SP500TotalReturnIndexreflectsnodeductionforfeesexpensesortaxesIndexMember_019ff6d2-46ce-7ea8-b8fb-8a7c4d713267" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
