from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To transfer responsibility or blame from oneself onto another; to absolve oneself of concern for a given matter by claiming to lack authority or jurisdiction.
May have originated with the game of poker, in which a marker or counter, frequently in frontier days a knife with a buckhorn handle, was used to indicate the person whose turn it was to deal. If the player did not wish to deal he could pass the responsibility by passing the "buckhorn" or "buck", as the marker came to be called, to the next player. (Wiktionary)