Action — The bets and / or raises at a poker table. "That table has a great deal of action" or "When you hit your Queen high flush, if you get any action, your opponent probably has a better hand." Also refers to the player whose turn it is to act. "The action is on the small blind."
Ante — A small forced bet placed by each player involved in a hand before any cards are dealt. The most common poker game that uses antes is 7 Card Stud, but they are also used in the later stages of many Texas holdem tournaments in addition to the blinds. Please note that antes are not the same as blinds.
All-In — In a no limit game, like no limit Texas holdem, to place a bet for all of the chips you have on the table. "I move all in." Also refers to a table stakes game, which means you can only play with the money you have on the table, where you have bet your last chips and there are still other players with more chips placing bets. In this case, you can only win the amount in the pot including your last bet and any calls of that bet. For example, if you place your last $10 in the pot at the beginning of the hand and there are three callers making the pot $40, no matter how much additional betting there is, you can only win $40. The remaining players are playing for both the $40 pot and the side pot, which is created from the additional betting action.
Backdoor — Usually used in a Texas holdem game referring to a straight or flush that is completed using both the turn and river card. For example, you hold the Ace and Queen of clubs and there is one club on the flop. If the turn and river are both clubs, you have completed a backdoor flush. It can be used in association with a draw, "I have a backdoor flush draw" or with a made hand, "He hit the backdoor straight." Also often called runner runner.
Bad Beat — When a hand that is a large favorite to win a pot is beaten. It is used in describing both the receiving and giving as in, "I received a bad beat" and "I was very lucky and gave him a bad beat." Examples of a bad beat are when a hand like AA loses to 55 or when a player flops three of a kind and an opponent hits a backdoor straight to beat them. Bad beat is also often used in a derogatory way as if to say the player who won had no business in the hand at all. Though many players will complain about receiving a bad beat even when they lose a pot where they are slight favorites, the truly bad beats are when you are a large favorite, not just with a five or ten percent edge.
Big Blind — The larger of two forced bets that are placed before any cards are dealt in Texas holdem and Omaha, as well as a few other less popular games. The big blind is two players to the left of the button, which signifies the acting dealer for the hand. It is usually twice the size of the small blind and is equal to the smaller of the two betting limits in limit Texas holdem. In a 2 / 4 limit Texas holdem game, the big blind would be 2. The blinds in no limit ring games are pre-determined by the house rules and in a tournament; they are determined by a set schedule, usually escalating as the tournament advances.
Blank — Usually referring to a turn or river card, a blank is a card that doesn't appear to help any players in the hand and doesn't work in co-ordination with the rest of the cards on the board. If the flop is three-suited, or rainbow, with an Ace, Jack and nine, if the turn is a three, it would be considered a blank, as it can't form a straight or flush. In the same hand, if the river is a six and doesn't make three of one suit on the board, it would also be considered a blank.
Blind — Used in all forms of Texas holdem and Omaha, as well as a few less popular variations of poker, a blind is a forced bet that is placed before a hand is dealt. There are usually two blinds, a small blind and a big blind, which are placed by the two players to the left of the dealer, or button. There are also a few places where there are three blinds and in a few games, there aren't small and big blinds, the blinds are of equal value. A blind is not the same thing as an ante, and can be used in conjunction with an ante, usually in the later rounds of tournaments.
Board — The board is all of the cards in the middle of the table that can be used by all of the players in the hand, often called community cards. The most common forms of poker using board cards are Texas holdem and Omaha.
Bottom Pair — Usually referring to the flop, but also occasionally for all community cards, bottom pair is when you match or "pair" the lowest card on the board with one from your hand. For example, if you hold a King and a five and the board is Queen seven five, you have bottom pair. Though not the same, the term bottom set is also used at times, signifying three of a kind when you have a pair in your hand and match the low card on the board.
Burn — After dealing the cards to the players at the table, mostly in Texas holdem and Omaha, the dealer places the top card of the deck face down into the muck or discard pile before each of the flop, turn and river. This prevents any chance of a player being able to see the top of the next card to prevent any type of cheating involving a marked deck. The term is often used in the phrase "Burn and turn" to signify burning the top card and turning over the next card.
Button — The token or disc that moves one space to the left after every hand to signify the player acting as the dealer for the hand. In games with an actual dealer, like at a casino, the button shows the player who has the advantage of acting last. In home games, the player with the button also often deals. This player is also often referred to as "The button" or "On the button."
Buy — A reference to making a raise in order to force all of your opponents to fold, as in "Buy the pot", or raising in order to force the opponents between you and the blinds to fold, as in "Buy the button." When you hear "Buy the pot", it is usually insinuating that the player is bluffing or is on a bluff, but generally when a player is trying to "Buy the button"; they have an above average hand.
Glossary courtesy of "Winning Low Limit Hold'em" by Lee Jones