Blackjack Glossary

Terms you hear at a blackjack table or read on this site. For the rules in order, read how to play blackjack.

Blackjack (natural): An ace and a ten-value card as your first two cards. Beats any other 21. Pays 3:2 at most tables.
Bust: A total over 21. The hand loses at once, even if the dealer busts later.
Hit: Take one more card.
Stand: Take no more cards.
Double down: Add a second bet equal to the first, take exactly one more card, and stand. Allowed on your first two cards.
Split: Separate two cards of equal value into two hands, each with a bet equal to the original.
Surrender: Give up your hand and lose half your bet. Late surrender, the common form, is offered after the dealer checks for blackjack.
Insurance: A side bet, offered when the dealer shows an ace, that the dealer has blackjack. Pays 2:1. Loses money over time unless you are counting.
Even money: A 1:1 payout on your blackjack, taken when the dealer shows an ace, in place of 3:2 or a push. The same bet as insurance, with the same loss.
Upcard: The dealer's face-up card. Basic strategy is your hand against this card.
Hole card: The dealer's face-down card.
Peek: The dealer checks the hole card for blackjack before anyone acts, when the upcard is an ace or a ten. The default rule on this site.
Soft hand: A hand with an ace counted as 11. Ace-6 is soft 17. The next card cannot bust it.
Hard hand: A hand with no ace, or with every ace counted as 1.
Stiff: A hard 12 through 16. One card can bust it. If you stand, it wins only when the dealer busts.
Push: A tie with the dealer. You get your bet back.
S17 and H17: Under S17 the dealer stands on soft 17. Under H17 the dealer hits it. H17 raises the house edge by about 0.2 percentage points.
DAS: Double after split. You may double down on a hand made by a split. Lowers the house edge.
RSA: Resplit aces. You may split again when a split ace draws another ace. Lowers the house edge.
6:5: A blackjack payout of 6:5 in place of 3:2. Adds about 1.4 percentage points to the house edge, more than any other common rule.
Shoe: The box that holds the shuffled decks in play, usually six or eight.
Penetration: How far into the shoe the dealer deals before the reshuffle. The count is most useful late in the shoe, so counting needs deep penetration.
Cut card: The plastic card placed in the shoe to mark the reshuffle point.
CSM: Continuous shuffle machine. Returns dealt cards to the shuffler after every round, so the count never builds and counting does not work.
House edge: The share of each initial bet the casino keeps on average over many hands. The house edge page lists it rule by rule.
Expected value (EV): The average result of a decision over unlimited repetitions. Basic strategy is the highest-EV action in every spot.
Basic strategy: The highest-EV play for every hand against every upcard, with no knowledge of the cards left in the shoe.
Index play: A play that departs from basic strategy when the count passes a set threshold, such as standing on 16 against a 10 when the true count is positive. Also called a deviation.
Running count: In Hi-Lo, the sum of the tags of every card seen so far: +1 for 2 through 6, 0 for 7 through 9, and −1 for tens and aces.
True count: The running count divided by the estimated decks remaining. The number that sets your bet size and your index plays.
Flat betting: Betting the same amount on every hand, whatever the count.
Bankroll: The money set aside for play. Your bet as a fraction of it sets your risk of ruin.
First base and third base: The seats to the dealer's left and right, first and last to act. Seat position does not change the math.
Toke: A tip for the dealer.