A player's turn to act. The action is on you. A willingness to gamble. I'll give you action or There's plenty of action in this game. A bet, along with all the calls of that bet. For example, if one player makes a $5 bet and three other players call, he is said to have $5 "in action", and to have received $15 worth of action on his bet. Usually this term comes into play when figuring side pots when one or more players is all in. See table stakes.