brash (adj.)youdaoicibaDictYouDict[brash 词源字典]
1824, of obscure origin, originally American English; perhaps akin to 16c. Scottish brash "attack, assault," or French breche "fragments," especially of ice, which is from a Germanic source (compare Old High German brehha "breach," from brehhan "to break"), or to German brechen "to vomit."[brash etymology, brash origin, 英语词源]