bratyoudaoicibaDictYouDict[brat 词源字典]
brat: [16] The origins of brat are not altogether clear, but it has plausibly been connected with the English dialect brat ‘makeshift or ragged garment’, as being the sort of apparel a rough or ill-mannered child might wear. This brat first appeared in late Old English as bratt, meaning ‘cloak’, a borrowing from Old Irish bratt ‘covering, mantle’.
[brat etymology, brat origin, 英语词源]
brat (n.)youdaoicibaDictYouDict
c. 1500, slang, "beggar's child," originally northern, Midlands and western England dialect word for "makeshift or ragged garment;" probably the same word as Old English bratt "cloak," which is from a Celtic source (compare Old Irish bratt "cloak, cloth"). The modern meaning is perhaps from notion of "child's apron." Hollywood Brat Pack (modeled on 1950s Rat Pack) is from 1985.