bucktooth (n.)youdaoicibaDictYouDict[bucktooth 词源字典]
1540s, from buck (n.1), perhaps on the notion of "kicking up," + tooth. In French, buck teeth are called dents à l'anglaise, literally "English teeth." Old English had twisel toð "with two protruding front teeth." Related: Buck-toothed.[bucktooth etymology, bucktooth origin, 英语词源]