buck: [OE] Old English had two related words which have coalesced into modern English buck: bucca ‘male goat’ and buc ‘male deer’. Both go back to a prehistoric Germanic stem *buk-, and beyond that probably to an Indo-European source. The 18th-century meaning ‘dashing fellow’ probably comes ultimately from the related Old Norse bokki, a friendly term for a male colleague, which was originally adopted in English in the 14th century meaning simply ‘fellow’. The colloquial American sense ‘dollar’ comes from an abbreviation of buckskin, which was used as a unit of trade with the Native Americans in Frontier days. => butcher[buck etymology, buck origin, 英语词源]