Definition of All-in
What is meant by the term "all-in" in poker? What is the definition of the term "all-in"?
In poker, the term "all-in" means that a player has put the last of their chips into the pot. When a player is "all-in", they can not perform another action because they don't have any chips left.
Let's give a few examples of situations where a player would be "all-in":

Example #2: You are playing in a $1/$2 NLHE cash game. You are currently in the SB.
Action folds around to the player on the button, who decides to put in a monster bet of 20x the BB. You look down at Ad-Kd and decide to push all-in. The BB folds as does the player on the button, who sheepishly admits that he only had 7-high.
By pushing "all-in", you committed all of your chips to the pot. If somebody had called you and had you "covered" (meaning, had as many chips as you did), then you could have potentially lost your entire stack.
--
Recent Articles That Include The Term All-in:
Garrett Adelstein vs Robbi Jade Lew Hand Explodes Into Mainstream Media
Phil Hellmuth Defeats Tom Dwan To Win $400,000 "High Stakes Duel" Match
Tom Dwan Ends Phil Hellmuth's "High Stakes Duel" Winning Streak
Phil Hellmuth vs Tom "durrrr" Dwan "High Stakes Duel" Match Set For August 25th
Chance Kornuth Concedes; Phil Galfond Wins Another "Galfond Challenge"
Back to the - Poker Dictionary