buck [OE] Buck seems to be a combination of Old English buc ‘male deer’ and bucca ‘male goat’. From the mid 19th century in poker a buck is an article placed as a reminder in front of a player whose turn it is to deal at poker. This is the buck in to pass the buck, ‘to shift the responsibility to someone else’—to pass the buck is to hand over the responsibility for dealing to the next player. The original buck may have been the handle of a buckhorn [OE] knife used as a marker, but its origin is uncertain. A related expression is the buck stops here. The US President Harry S. Truman had this as a motto on his desk, indicating that the ultimate responsibility for running the country lay with him. The phrases buck up [M19th] and buck up one’s ideas [M20] have a connection with the sharp jerk of the buck’s butting movements, while the verb to buck [M19th] seems to have come from the way a buck jumps. Why a US dollar has been known as a buck from the mid 18th century is unclear, but it may have been from the use of buckskins as a medium of exchange particularly among frontiersmen and Native Americans.