Blackjack Glossary: Every Term You Need to Know
From bust to true count, every term you'll encounter reading strategy guides, at the casino table, or in the card counting literature — with precise, usable definitions.
Put these terms into practice with real simulation.
21simulator.com is a full blackjack strategy engine — test any concept from this glossary with simulated hands.
Open Simulator → 21simulator.com is a full blackjack strategy engine — test any concept from this glossary with simulated hands.
A–Z Reference
| Term | Definition |
|---|---|
| Bankroll | The total amount of money a player has set aside for gambling. Proper bankroll management is the foundation of risk control. |
| Basic Strategy | The mathematically optimal decision for every hand against every dealer upcard. Playing basic strategy reduces the house edge to ~0.5%. |
| Bet Spread | The ratio between a card counter's minimum and maximum bet. A 1–12 spread means betting 12× the minimum at the highest advantage. |
| Blackjack (Natural) | An Ace plus any 10-value card on the initial two-card deal. Traditionally pays 3:2. A player blackjack beats a dealer 21 achieved with 3+ cards. |
| Bust | Any hand total exceeding 21. A player bust is an immediate loss; a dealer bust pays all surviving player hands. |
| Cold Deck | Slang for a shoe yielding many dealer wins. Has no statistical meaning — decks don't run hot or cold over meaningful sample sizes. |
| Cut Card | A plastic card inserted into the shoe to mark the reshuffle point. Card counters prefer a cut card placed near the back (deep penetration). |
| DAS (Double After Split) | A rule that allows doubling down after splitting a pair. DAS reduces the house edge by ~0.14% and changes several pair splitting decisions. |
| Double Down | Doubling the original bet and receiving exactly one more card. Available on any first two cards in most games; restricted to 10 and 11 in some. |
| Early Surrender | Surrendering before the dealer checks for blackjack. Rare rule that adds significant player value (~0.6%). Virtually nonexistent in modern casinos. |
| Edge (House Edge) | The casino's mathematical advantage, expressed as a percentage of each bet. In blackjack, the house edge against basic strategy is roughly 0.4–0.65% depending on rules. |
| ENHC (European No Hole Card) | A rule variant where the dealer takes a second card only after all players act. Changes doubling and splitting strategy slightly due to blackjack exposure risk. |
| EV (Expected Value) | The average result of a decision repeated infinitely. Positive EV = profitable in the long run. Negative EV = losing in the long run. |
| Flat Bet | Wagering the same amount on every hand. Minimizes variance and is optimal for basic-strategy players who are not counting. |
| H17 (Hits Soft 17) | A rule requiring the dealer to hit any soft 17 hand. Increases house edge by 0.22% compared to S17. Common on Las Vegas Strip shoe games. |
| Hard Hand | Any hand without an Ace, or one where the Ace can only count as 1 without busting. Hard 16 is the most commonly misplayed hand. |
| Hi-Lo | The most widely used card counting system. Cards 2–6 are tagged +1; 7–9 are 0; 10-value cards and Aces are −1. |
| Hole Card | The dealer's face-down card. In American blackjack, the dealer peeks at the hole card before players act when showing an Ace or 10. |
| Insurance | A side bet offered when the dealer shows an Ace. Pays 2:1 if the dealer has blackjack. Carries a 7.4% house edge — never correct except for card counters. |
| Late Surrender | Surrendering after the dealer checks for blackjack. Correct in specific situations (hard 16 vs 10, hard 15 vs 10) and reduces house edge by ~0.07%. |
| Martingale | A betting system that doubles the bet after every loss. Does not change house edge; increases variance and risks table maximum in a losing streak. |
| Natural | See Blackjack. A two-card hand totaling 21. |
| Penetration | The percentage of a shoe dealt before reshuffling. 75% penetration means three-quarters of cards are dealt. Higher penetration is better for card counters. |
| Pit Boss | Casino supervisor who monitors table games for cheating, errors, and unusual play. Card counters playing high spreads attract pit attention. |
| Push | A tie between the player and dealer. The player's bet is returned. Also called a "standoff." |
| Running Count | In card counting, the cumulative sum of tags seen since the last shuffle. Must be converted to a true count to make correct betting and strategy decisions. |
| S17 (Stands Soft 17) | A rule requiring the dealer to stand on all 17s, including soft 17. Reduces house edge by 0.22% vs H17. Preferred for players. |
| Shoe | A dealing device that holds multiple decks. Most casino blackjack is dealt from a 6 or 8-deck shoe. |
| Soft Hand | Any hand containing an Ace counted as 11. Soft 18 (Ace-7) is the most commonly misplayed soft hand. |
| Split | Dividing a pair into two separate hands, each with an independent bet equal to the original. Always split Aces and 8s; never split 5s or 10s. |
| Surrender | Folding a hand after the first two cards, forfeiting half the bet. See also: early surrender, late surrender. |
| True Count | The running count divided by the number of remaining decks. The true count is the decision-making count for betting and strategy deviations. |
| Upcard | The dealer's face-up card, visible to all players. Basic strategy decisions are based on your hand total and the dealer's upcard. |
| Variance | The spread of outcomes around the expected value. High variance = wider swings. Bet sizing and session length affect how much variance you experience. |
| Stand | Taking no more cards on your current hand. You are satisfied with your total. Signal to the dealer with a horizontal wave of the hand. |
| Hit | Requesting another card from the dealer. You tap the felt to signal a hit. You may hit repeatedly until you stand, bust, or are otherwise resolved. |
| Even Money | A 1:1 payout — you win exactly your bet amount. Standard winning hands pay even money. Also a term for accepting even money on a blackjack when the dealer shows an Ace (equivalent to taking insurance; decline it). |
| CSM (Continuous Shuffling Machine) | A device that shuffles returned cards back into the shoe after each hand, eliminating deck penetration entirely. Card counting is impossible against a CSM. |
| RNG (Random Number Generator) | The algorithm that determines card order in online blackjack. Licensed online casinos use certified RNGs — each hand is dealt from a freshly randomized deck. |
| Comp | Complimentary benefit (free meals, hotel stays, cashback) awarded by casinos to players based on their theoretical losses. Comps reduce but never eliminate the house edge. |
Terms That Confuse Beginners Most
Hard vs Soft
A soft hand contains an Ace counting as 11 — the Ace can safely drop to 1 if you take a card that would otherwise bust you. A hard hand has no such safety net. Soft 17 (Ace-6) is a very different situation from hard 17 (10-7): basic strategy says hit or double on soft 17, but always stand on hard 17.
Running Count vs True Count
Card counters maintain a running count — a cumulative tag tally from the start of the shoe. But a running count of +10 means much more when half the shoe remains (2 decks) than when almost all cards have been played (8 decks). The true count divides the running count by remaining decks to normalize: true count = running count ÷ decks remaining. Bet sizing and strategy deviations should be based on the true count, not the raw running.
Penetration
Penetration describes how deep into the shoe the dealer deals before reshuffling. It matters to card counters because the advantage from a high true count is only realizable if enough cards are dealt to establish that count consistently. A 6-deck shoe with 75% penetration (4.5 decks dealt) is significantly more exploitable than the same shoe dealt to 50%.
Push
A push is a tie — your hand equals the dealer's hand. No money changes hands; your bet is returned. Pushes are not losses. A session that feels "up and down" often has a high push rate that makes it seem like more action is occurring than it is.