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O.E. bucca “male goat,” from P.Gmc. *bukkon (cf. M.Du. boc, O.H.G. boc, O.N. bokkr), perhaps from a PIE base *bhugo (cf. Avestan buza “buck, goat,” Arm. buc “lamb”), but some speculate that it is from a lost pre-Gmc. language. Apparently O.E. also had buc “male deer.” The two words (if truly separate) were fully merged by c.1100. Verb is 1848, apparently with a sense of “jump like a buck.” Meaning of “dollar” is 1856, Amer.Eng., perhaps an abbreviation of buckskin, a unit of trade among Indians and Europeans in frontier days, attested in this sense from 1748. Buckshot is first recorded 1447; buck up “cheer up” is from 1844. Pass the buck is first recorded in the lit. sense 1865, Amer.Eng.:
“The ‘buck’ is any inanimate object, usually knife or pencil, which is thrown into a jack pot and temporarily taken by the winner of the pot. Whenever the deal reaches the holder of the ‘buck’, a new jack pot must be made.” [J.W. Keller, “Draw Poker,” 1887]
The fig, sense of “shift responsibility” is first recorded 1912.