Exactly right, precisely, as in Her review of the book was right on the button, or We're supposed to be there at six o'clock on the button. This term may come from boxing, where a punch on the button means "a punch on the chin." [Colloquial; c. 1900] Also see
on the dot.
The player who holds the dealer button.
SoundPoker Says: In games like hold'em and omaha the dealer button moves one position (usually to the left) after each hand is played. Depending on how long a player is at a particular seat they could be "on the button" many times in a particular poker session.
See Also: Button, Dealer, Position, The Button