Buck
Buck is an old name for the button.
The simple explanation
Buck is an old name for the dealer button. It was originally a knife with a buckhorn handle that was passed to the next player to mark the dealer. The phrase 'pass the buck' comes from this practice, and so does 'the buck stops here'.
A closer look
The word is rarely heard at modern tables, where the marker is a disc called the button. The history is a good example of how poker words enter everyday English. President Harry Truman, an avid poker player, kept a sign on his desk reading 'The buck stops here', meaning that he took the final responsibility. In poker, passing the buck meant passing the deal to the next player.
A practical example
A player says, 'The buck is on you,' meaning the button has reached them.
Full explanation
Buck is an old name for the button.
Buck is an old, colloquial name for the dealer button. The original button was a clasp knife with a buckhorn handle, which was passed from player to player to show who dealt.
The phrase ‘pass the buck’ comes from this custom. A player who did not want the deal could pass the knife on, and the buck was a sign of responsibility.
President Harry Truman, a poker player, popularized the saying ‘the buck stops here’ to mean that he accepted final responsibility.
Today players say button, and the word buck belongs to the history of the game.