bangs (n.)youdaoicibaDictYouDict[bangs 词源字典]
"hair cut straight across the forehead," 1878 (singular), American English, attested from 1870 of horses (bang-tail), perhaps from notion of abruptness (as in bang off "immediately, without delay," though this expression is attested only from 1886). See bang.[bangs etymology, bangs origin, 英语词源]