Main Entry: an·cil·lary

Pronunciation: \ˈan(t)-sə-ˌler-ē, -ˌle-rē, especially British an-ˈsi-lə-rē\

Function: adjective

Date: 1667

1 : subordinate, subsidiary <the main factory and its ancillary plants>
2 : auxiliary, supplementary <the need for ancillary evidence>

— ancillary noun