Brat
mid 16th century: perhaps an abbreviation of synonymous Scots bratchet, from Old French brachet ‘hound, bitch’; or perhaps from dialect brat ‘rough garment, rag’, based on Old Irish bratt ‘cloak’.
wiktionary
Early Modern English (ca. 1500) slang term meaning "beggar's child". Possibly from Scots bratchet(“bitch, hound”). Or, possibly originally a dialectal word, from northern and western England and the Midlands, for a "makeshift or ragged garment," from Old English bratt(“cloak”), which is from a Celtic source (Old Irish brat(“cloak, cloth”)).
Shortened from bratwurst, from German Bratwurst.
brat (plural brats)
brat
etymonline
brat (n.)
c. 1500, "beggar's child" ("... wyle beggar with thy brattis ...), originally slang, from a 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 transferred meaning is perhaps from notion of "child's apron." Hollywood Brat Pack (modeled on 1950s Rat Pack) is from 1985. Brattery "nursery" is attested from 1788.
