white bread (n.)youdaoicibaDictYouDict[white bread 词源字典]
c. 1300, as opposed to darker whole-grain type, from white (adj.) + bread (n.). Its popularity among middle-class America led to the slang adjectival sense of "conventional, bourgeois" (c. 1980). Old English had hwitehlaf.[white bread etymology, white bread origin, 英语词源]