subsidiary (adj.)youdaoicibaDictYouDict[subsidiary 词源字典]
1540s, from Latin subsidiarius "belonging to a reserve, of a reserve, reserved; serving to assist or supplement," from subsidium "a help, aid, relief, troops in reserve" (see subsidy). As a noun, c. 1600, "subsidiary thing." In Latin the word was used as a noun meaning "the reserve."[subsidiary etymology, subsidiary origin, 英语词源]