Casino Glossary

A

Advantage Play

Legal techniques that give a player a real mathematical edge over the house, such as card counting or choosing a video poker machine with a favorable pay table. Casinos usually respond by limiting bets, changing rules or refusing play.

All-In

A poker move in which a player bets every chip they have in front of them. A player who is all-in can only win the part of the pot they were able to match.

American Odds

An odds format, also called moneyline odds, that uses positive and negative numbers. +150 means a $100 stake wins $150 profit, while −200 means you must stake $200 to win $100 profit.

American Roulette

A roulette wheel with 38 pockets: 1 to 36, a single zero and a double zero. The extra pocket raises the house edge on almost every bet to 5.26%, compared with 2.70% on a single-zero wheel.

Any Craps

A one-roll craps bet that the next roll will be 2, 3 or 12. It usually pays 7 to 1 and carries a house edge of about 11.11%.

Any Seven

A one-roll craps bet that the next roll totals 7. It pays 4 to 1 against true odds of 5 to 1, giving it one of the highest edges on the table at about 16.67%.

B

Baccarat

A card game in which players bet on whether the Banker hand or the Player hand will finish closer to 9, or on a tie. Drawing follows fixed rules, so the only decision is which bet to make.

Banker Bet

A baccarat wager that the Banker hand will win. It wins slightly more often than the Player bet, so casinos usually take a 5% commission on winnings, leaving a house edge of about 1.06%.

Bankroll

The total amount of money set aside specifically for gambling. How large it is relative to your bet size largely decides how long it lasts and how likely it is to be wiped out.

Basic Strategy

The mathematically best way to play each blackjack hand based on your cards and the dealer's upcard. Following it cuts the house edge to roughly 0.3% to 1%, depending on the table rules.

Big 6 and Big 8

Craps bets that a 6, or an 8, will be rolled before a 7. They pay even money against true odds of 6 to 5, for a house edge of about 9.09%. Placing the 6 or 8 covers the same outcome at a 1.52% edge.

Big Six Wheel

A large upright wheel, sometimes called a money wheel, where players bet on which symbol or number the pointer will stop on. House edges are high, roughly 11% to 24% depending on the bet.

Binomial Distribution

The probability distribution for the number of successes in a fixed number of independent trials that each have the same chance of success. It describes, for example, how many times red appears in 100 roulette spins.

Blackjack

A card game in which players try to beat the dealer by getting closer to 21 without going over. The word also means a two-card 21, an ace plus a ten-value card, which traditionally pays 3 to 2.

Blinds

Forced bets posted before the cards are dealt in games like Texas Hold'em, usually by the two players to the left of the dealer button. They make sure every pot has money to compete for.

Blocking Software

Programs or apps that stop a device from opening gambling websites and apps. The added friction can help someone stick to a decision to cut back or stop.

Bluff

A bet or raise made with a weak hand to persuade opponents holding better hands to fold. Bluffing only works in games where players compete against each other rather than the house.

Bonus Round

A special slot feature, triggered by certain symbols, that offers extra spins, a pick-and-win screen or another mini-game. Its payouts are already counted in the machine's overall RTP.

Bookmaker

A person or business that accepts bets on sports and other events at set odds. Bookmakers build a margin into their prices so that balanced betting earns them a profit whatever the result.

Break-Even Probability

The win rate a bet needs for its expected value to be exactly zero. For a standard −110 sports bet it is 110 ÷ 210, or about 52.38%.

Burn Card

A card taken from the top of the deck and set aside unseen before dealing. It is a routine security step that makes the next card harder to know or predict.

Bust

Going over 21 in blackjack, which is an automatic loss for a player. Because players act first, a player who busts loses even if the dealer busts later, which is a key source of the house edge.

C

Cage

The casino's secure cashier area, where chips are exchanged for cash, markers are processed and large payouts are handled.

Card Counting

Tracking the balance of high and low cards left in a blackjack shoe to spot moments when the remaining cards favor the player. It is legal in most places, but casinos can ban counters, shuffle early or limit their bets.

Casino War

A simple card game in which the player and dealer each get one card and the higher card wins. Going to war on ties gives a house edge of about 2.88%.

Chasing Losses

Continuing to gamble, often with bigger bets, to try to win back money already lost. Since every bet still carries a house edge, chasing usually deepens losses, and it is a common warning sign of problem gambling.

Chip

A token used instead of cash at casino tables, with colors marking different values. Chips speed up play and improve security, but they also make money feel less real, which can encourage bigger bets.

Coin-In

The total amount bet on a slot machine over a period, the slot version of handle. Slot hold is usually measured as a percentage of coin-in.

Column Bet

An outside roulette bet on one of the three vertical columns of 12 numbers on the layout. It pays 2 to 1 and, like every bet on a European wheel, carries a 2.70% house edge.

Combination

A way of choosing items where order does not matter, written C(n, k). For example, C(49, 6) = 13,983,816 is the number of possible tickets in a 6/49 lottery.

Come Bet

A craps bet that works like a Pass Line bet but is made after the point is set. The next roll acts as its own come-out roll, and the house edge is about 1.41%.

Come-Out Roll

The first roll of a new round in craps. A 7 or 11 wins for Pass Line bets, a 2, 3 or 12 loses, and any other total becomes the point.

Commission

A fee taken from winning bets, most commonly the 5% charged on winning Banker bets in baccarat. It exists because the Banker hand wins slightly more often than the Player hand.

Comps

Short for complimentaries: free rooms, meals, drinks, shows or play given to customers. Casinos base comps on a fraction of a player's theoretical loss, so they are a rebate on expected losses rather than a gift.

Continuous Shuffling Machine

A device that returns used cards to the deck after every round, so the shoe never runs down. It makes card counting ineffective and removes pauses for shuffling, which means more hands per hour.

Cooling-Off Period

A short, voluntary pause on gambling, often from a day to several weeks, that an account holder can set with an operator. It gives a break without the longer commitment of self-exclusion.

Corner Bet

An inside roulette bet on a block of four numbers that meet at a corner on the layout. It pays 8 to 1.

Craps

A dice game in which players bet on the results of rolls of two dice. The word also refers to a come-out roll of 2, 3 or 12, which loses for Pass Line bettors.

Credit

The unit a slot machine uses to show your balance and bets. One credit is worth the machine's denomination, so 500 credits on a one-cent machine equals $5.

Croupier

The casino employee who runs a table game, for example spinning the roulette wheel, dealing cards, collecting losing bets and paying winners.

D

D'Alembert System

A betting progression in which you raise your bet by one unit after a loss and lower it by one unit after a win. Its swings are gentler than the Martingale's, but it cannot change the house edge.

Decimal Odds

An odds format that shows the total return per unit staked, stake included. Decimal odds of 2.50 return $2.50 for every $1 bet, which implies a 40% probability.

Denomination

The value of one credit on a slot or video poker machine, such as one cent, five cents or one dollar. Your actual bet per spin is the denomination times the number of credits played.

Deposit Limit

A cap you set on how much money can be added to a gambling account per day, week or month. It is one of the simplest tools for keeping online play inside a budget.

Deuces Wild

A video poker game in which all four 2s act as wild cards. The full-pay version returns about 100.76% with perfect strategy, but it is rare, and weaker pay tables return less.

Don't Come

A craps bet that works like Don't Pass but is placed after the point is set. It wins if a 7 arrives before its point number, with a house edge of about 1.36%.

Don't Pass

A craps bet against the shooter. It wins on a come-out 2 or 3, ties on 12, and once a point is set wins if a 7 comes before the point. The house edge is about 1.36%.

Double Down

A blackjack option to double your original bet in exchange for exactly one more card. Basic strategy uses it on strong starting totals, such as 11, when the dealer shows a weaker upcard.

Dozen Bet

An outside roulette bet on 1-12, 13-24 or 25-36. It pays 2 to 1.

Drop

The total cash and credit exchanged for chips at the tables or inserted into slot machines. Table hold is usually measured against drop rather than against total bets.

E

Element of Risk

The house edge measured against the total amount actually risked, including extra money added by doubling, splitting or raising. It gives a fairer comparison between games where the final bet can grow.

En Prison

A French roulette rule for even-money bets: when zero comes up, your bet is held for one more spin instead of being lost. Like La Partage, it cuts the house edge on those bets to about 1.35%.

Equity

Your share of the pot based on the chance that your hand wins from the current point. Pocket aces, for example, have roughly 82% equity against pocket kings before the flop.

European Roulette

A roulette wheel with 37 pockets: 1 to 36 and a single zero. Every bet carries a house edge of 1/37, about 2.70%.

Even Money (Blackjack)

An offer to take a guaranteed 1 to 1 payout on your blackjack when the dealer shows an ace. It is mathematically the same as taking insurance and carries the same house edge.

Even-Money Bet

Any bet that pays 1 to 1, such as red or black in roulette or the Pass Line in craps. A winning $10 even-money bet returns your $10 plus $10 profit.

Expected Loss

The average amount you should expect to lose over a stretch of play, equal to the total amount wagered times the house edge. For example, $1,000 wagered at a 2.70% edge has an expected loss of $27.

Expected Value (EV)

The average result of a bet if it were repeated many times, found by weighting each outcome by its probability. Almost every casino bet has a negative EV for the player.

Eye in the Sky

Casino slang for the ceiling-mounted surveillance cameras that watch tables, machines and cash handling.

F

Fair Game

A bet with an expected value of exactly zero, where payouts match true odds. Casino games are deliberately not fair in this sense, with the free odds bet in craps as a rare exception.

Fibonacci System

A betting progression that follows the sequence 1, 1, 2, 3, 5, 8 and so on, moving one step forward after a loss and two steps back after a win. It reshapes the swings without beating the house edge.

Field Bet

A one-roll craps bet that the next roll will be 2, 3, 4, 9, 10, 11 or 12. With 2 and 12 paying 2 to 1, the house edge is about 5.56%; if 12 pays 3 to 1, it drops to about 2.78%.

Five-Number Bet

A bet on 0, 00, 1, 2 and 3, found only on American wheels. It pays 6 to 1 and has a house edge of about 7.89%, the worst bet on the American layout.

Flat Betting

Betting the same amount on every decision regardless of earlier results. It keeps the expected loss predictable and avoids the large swings of progressive systems.

Flop

In Texas Hold'em, the first three community cards, dealt face up together and followed by a round of betting.

Flush

A poker hand of five cards of the same suit that are not in sequence. There are 5,108 flushes among the 2,598,960 possible five-card hands.

Four of a Kind

A poker hand containing all four cards of one rank. There are 624 four-of-a-kind hands among the 2,598,960 possible five-card hands.

Fractional Odds

An odds format that shows profit relative to stake, such as 3/2, which pays $3 profit for every $2 bet. Fractional 3/2 equals decimal 2.50 and an implied probability of 40%.

Free Odds

An extra craps bet placed behind a Pass, Don't Pass, Come or Don't Come bet once a point is set. It pays true odds, so its house edge is 0%, which makes it a rare fair bet in the casino.

Free Spins

Slot spins awarded by a bonus feature that do not cost extra credits. Their value is already built into the machine's overall return.

Full House

A poker hand of three cards of one rank plus two of another, such as three kings and two fives. There are 3,744 possible full houses.

Full Pay

A video poker pay table offering the best standard payouts for that game, such as 9/6 Jacks or Better. Small pay table cuts can lower the long-run return by more than two percentage points.

G

Gambler's Fallacy

The mistaken belief that past results change the odds of independent future events, such as thinking black is due after a run of red. Each spin, roll or flip has the same probability whatever came before.

Gambling Disorder

The clinical term for persistent gambling that causes significant distress or harm. The DSM-5, published in 2013, classifies it alongside substance-related and addictive disorders, and only a qualified professional can diagnose it.

H

Handle

The total amount of money wagered over a period, counting every bet. Because players re-bet the same money, handle is usually far larger than the cash they bring.

Hard Hand

A blackjack hand with no ace, or with an ace that can only count as 1. A hard 16 is one of the weakest hands in the game.

Hardway

A craps bet that 4, 6, 8 or 10 will be rolled as a pair, such as 3 and 3 for a hard 6, before a 7 or the easy version of that number. Hard 6 and 8 carry about a 9.09% edge; hard 4 and 10 about 11.11%.

Hi-Lo Count

The most widely used card counting system. Cards 2 through 6 count +1, 7 through 9 count 0, and tens and aces count −1, with the total adjusted for the decks remaining.

High Card

A poker hand with no pair, straight or flush, ranked by its highest card. There are 1,302,540 such hands, about half of all five-card hands.

High Roller

A player who bets large amounts. High rollers often receive generous comps and special terms because their theoretical loss is large.

Hit

To take another card in blackjack. Basic strategy says to hit hard 12 through 16 against a dealer 7 or higher, among other spots.

Hit Frequency

The share of spins or hands on a machine that return any payout at all. A high hit frequency does not mean a high return, because many hits pay less than the bet.

Hold

The share of money a casino keeps, usually expressed at table games as win divided by drop. Because chips are bet over and over, hold percentages run much higher than the house edge on individual bets.

Hole Card

The dealer's face-down card in blackjack. In many games the dealer checks it for blackjack when showing an ace or a ten-value card.

Hot-Hand Fallacy

The belief that a person or table on a winning streak is more likely to keep winning in a game of pure chance. With independent events, a streak says nothing about the next result.

House Edge

The average percentage of each bet the casino expects to keep over the long run. It comes from paying winners less than true odds, such as 35 to 1 on a European roulette number that is a 36 to 1 shot.

I

Illusion of Control

The tendency to believe you can influence outcomes that are actually random, for instance by throwing dice a certain way or stopping slot reels at just the right moment.

Implied Odds

In poker, a version of pot odds that also counts the money you expect to win on later betting rounds if you complete your draw.

Implied Probability

The probability of an outcome suggested by its odds. Decimal odds of 2.50 imply 1 ÷ 2.50 = 40%, and American odds of −200 imply about 66.7%.

Independent Events

Events where the result of one has no effect on the probability of another. Roulette spins, dice rolls and slot spins are all independent.

Inside Bets

Roulette bets on specific numbers or small groups of numbers, such as straight-up, split, street, corner and six-line bets. They pay more than outside bets but win less often.

Insurance

A blackjack side bet, offered when the dealer shows an ace, that pays 2 to 1 if the dealer has blackjack. Its house edge is roughly 7%, so basic strategy declines it.

J

Jacks or Better

The classic video poker game, in which a pair of jacks or higher is the lowest paying hand. The 9/6 version returns about 99.54% with optimal play, while 8/5 returns about 97.30%.

K

Kelly Criterion

A formula for sizing bets to grow a bankroll as fast as possible over the long run when you hold a genuine edge. For an even-money bet it stakes a fraction of the bankroll equal to the edge, so with no edge, as in nearly all casino bets, the Kelly bet is zero.

Keno

A lottery-style game in which players pick numbers and the house draws 20 numbers from 80. House edges are commonly 25% to 30% or more.

Kicker

A side card used to break ties between hands of the same rank, such as the highest unpaired card when two players both hold a pair of aces.

L

La Partage

A French roulette rule that returns half of an even-money bet when the ball lands on zero. It cuts the house edge on those bets from 2.70% to about 1.35%.

Labouchère System

A betting progression in which you write a list of numbers, bet the sum of the first and last, cross them off after a win and add the lost amount to the list after a loss. Losing runs can demand very large bets.

Law of Large Numbers

The principle that as the number of trials grows, the average result moves closer to the expected value. It is why casinos with millions of bets earn close to the house edge while individual short sessions vary widely.

Loss Disguised as a Win

A slot outcome that pays back less than the total bet but is celebrated with sounds and animations. Betting $2 and winning $0.80 is a net loss of $1.20, even though the machine treats it as a win.

Loss Limit

The most you allow yourself to lose in a session, day or trip, decided before you start. Once you reach it, you stop playing.

Loss Rebate

A deal, usually offered to high rollers, in which the casino returns a share of a player's net losses. It trims the effective house edge in exchange for large volume.

Lottery

A game of chance in which players buy tickets and winners are drawn at random. Lotteries commonly return around half of sales as prizes, and a 6/49 jackpot is a 1 in 13,983,816 shot.

Loyalty Program

A casino rewards scheme that tracks your play and awards points, tiers and comps. Rewards are based on theoretical loss, so earning more usually means losing more on average.

M

Marker

A line of credit a casino extends to an approved player, signed like a check and repaid later. A marker is borrowed money and is treated as a debt.

Martingale System

A progression in which you double your bet after every loss to recover earlier losses plus one unit. It wins small amounts often but eventually meets a losing streak or table limit that causes a large loss, and its expected value stays negative.

Mini-Baccarat

A smaller, faster version of baccarat played at a standard-size table with lower limits, where the dealer handles all the cards. With the same rules, the odds match the full game.

Moneyline

A sports bet on which side will win outright, usually quoted in American odds. Favorites carry negative numbers and underdogs positive numbers.

N

Natural (Baccarat)

A two-card total of 8 or 9 in baccarat. A natural ends the hand at once, with no further cards drawn.

Near Miss

A losing outcome that looks close to a win, such as two jackpot symbols with the third just off the payline. In a random game it says nothing about the next spin, yet it can make players feel they are getting close.

Negative Expectation

A bet whose expected value is below zero, meaning it loses money on average over time. Nearly every casino wager is a negative-expectation bet for the player.

Normal Distribution

The bell-shaped curve that the total result of many independent bets tends to follow. About 95% of outcomes fall within two standard deviations of the average, which makes it handy for estimating session swings.

O

Odds

A way of expressing likelihood as a ratio, such as 5 to 1 against, meaning five ways to lose for each way to win. Casinos also use odds to state payouts, which are usually shorter than true odds.

One Pair

A poker hand containing exactly one pair. It is the most common made hand, with 1,098,240 combinations among 2,598,960 five-card hands.

Outs

The unseen cards that would improve your poker hand to a likely winner. A flush draw after the flop usually has 9 outs.

Outside Bets

Roulette bets on large groups of numbers, such as red or black, odd or even, high or low, dozens and columns. They win more often than inside bets but pay less.

Overround

The amount by which the implied probabilities of every outcome in a betting market add up to more than 100%. On a −110/−110 line each side implies 52.38%, for an overround of about 4.76%.

P

Pair Plus

A Three Card Poker side bet that pays according to the strength of your own hand, regardless of the dealer. With a 1-4-6-30-40 pay table, the house edge is about 2.32%.

Pari-Mutuel Betting

A pool system in which all bets on an event go into a shared pot, the operator takes a cut, and the rest is split among winning tickets. The odds are set by the betting itself rather than by a bookmaker.

Parlay

A single bet that links two or more wagers, all of which must win for it to pay. Payouts multiply, and so does the bookmaker's margin.

Paroli System

A positive progression, also called a reverse Martingale, in which you double your bet after each win and drop back to the base bet after a loss or a set number of wins. It keeps losses small but does not change the house edge.

Pass Line

The basic craps bet with the shooter. It wins on a come-out 7 or 11, loses on 2, 3 or 12, and otherwise wins if the point repeats before a 7. The house edge is about 1.41%.

Pay Table

The chart showing what each winning combination pays on a slot or video poker machine. On video poker, the pay table lets you calculate the exact long-run return.

Payline

A line across a slot machine's reels on which matching symbols must land to pay. Modern machines may have dozens of paylines or pay on matching symbols in adjacent reels.

Penetration

How far into a shoe the dealer deals before reshuffling, often given as a percentage of the cards. Deeper penetration helps card counters, which is one reason casinos shuffle early.

Pit

The area enclosed by a ring of table games, where dealers, supervisors and chip supplies are based. Players stay on the outside.

Pit Boss

A supervisor who oversees a group of table games, watching for mistakes and cheating, approving large transactions and rating players for comps.

Place Bet

A craps bet that a chosen number, 4, 5, 6, 8, 9 or 10, will be rolled before a 7. Placing the 6 or 8 carries a 1.52% edge, the 5 or 9 about 4.00%, and the 4 or 10 about 6.67%.

Player Bet

A baccarat wager that the Player hand will win. It pays even money with no commission and has a house edge of about 1.24%.

Player's Card

A card you insert into machines or present at tables so the casino can record how much and how long you play. It has no effect on game outcomes; it only feeds the comp calculation.

Pocket Cards

The two private cards dealt face down to each player in Texas Hold'em, also called hole cards. The chance of being dealt any pocket pair is 1 in 17.

Point

In craps, the number, 4, 5, 6, 8, 9 or 10, set on the come-out roll. The shooter keeps rolling until the point repeats or a 7 appears.

Point Spread

A handicap applied in a sports bet, where the favorite must win by more than the spread for bets on it to pay, and the underdog can lose by less than the spread and still cover.

Pot Odds

The ratio of the money in the pot to the cost of a call. Comparing pot odds with your chance of completing a draw shows whether calling pays off in the long run.

Probability

A number from 0 to 1, or 0% to 100%, describing how likely an event is. The chance of rolling a 7 with two dice is 6/36, or about 16.67%.

Problem Gambling

Gambling that harms a person's finances, relationships, work or wellbeing. It sits on a spectrum, and it does not need a formal diagnosis to be worth addressing.

Progressive Betting System

Any strategy that changes bet size based on earlier results, such as the Martingale or Fibonacci. None can turn a negative-expectation game into a positive one.

Progressive Jackpot

A jackpot that grows as a small part of each bet is added to it, often across many linked machines. The odds of winning it are typically very long.

Punto Banco

The most common casino form of baccarat, in which the house banks the game and all drawing follows fixed rules. Punto means Player and banco means Banker.

Push

A tie in which your bet is returned with no win or loss, such as when you and the blackjack dealer both finish on 19.

Q

Quick Pick

A lottery or keno ticket with numbers chosen at random by a machine. It has exactly the same chance of winning as numbers you choose yourself.

R

Rake

The fee a card room takes from each poker pot, or charges by time, for hosting the game. Because players compete against each other, the rake is how the house earns money.

Random Number Generator (RNG)

Software or hardware that produces unpredictable numbers used to decide outcomes in electronic games. In regulated markets, RNGs are typically tested by independent labs.

Reality Check

A pop-up reminder, common in online gambling, that shows how long you have been playing and often your net result. It is designed to break the spell of continuous play.

Reel

One of the vertical spinning columns of symbols on a slot machine. On modern machines a random number generator picks the stopping positions, and the spin animation simply displays the result.

Responsible Gambling

An approach that treats gambling as paid entertainment within limits set in advance, supported by tools such as deposit limits, reality checks and self-exclusion.

Return to Player (RTP)

The percentage of all money wagered on a game that is paid back to players over the long run. A 96% RTP means a 4% house edge, and individual sessions can land far from it.

Risk of Ruin

The probability of losing an entire bankroll before reaching a goal or within a set amount of play. It rises with larger bets relative to bankroll, higher variance and a bigger house edge.

River

The fifth and final community card in Texas Hold'em, followed by the last round of betting.

Royal Flush

The highest poker hand: ace, king, queen, jack and ten of the same suit. There are only 4 among the 2,598,960 possible five-card hands.

Rule of 2 and 4

A Texas Hold'em shortcut for estimating the chance of hitting a draw: multiply your outs by 4 on the flop when two cards are to come, or by 2 with one card left. Nine outs on the flop gives about 36%, close to the true figure of about 35%.

Running Count

The raw total of card values in a counting system such as Hi-Lo, kept from the start of a shoe. Dividing it by the decks remaining gives the true count.

S

Scatter Symbol

A slot symbol that pays or triggers a feature wherever it lands on the reels, rather than only on a payline.

Self-Exclusion

A voluntary agreement to be barred from a casino, gambling site or group of operators for a set period, often months or years. It is one of the strongest tools for someone who wants a firm break from gambling.

Set

Three of a kind made with a pocket pair plus one matching community card. A pocket pair flops a set about 11.8% of the time.

Seven Out

Rolling a 7 after a point has been set in craps. It ends the shooter's turn and loses Pass Line bets and Come bets that have points.

Shoe

A box that holds several decks of cards for dealing, used in blackjack and baccarat. More decks slightly raise the blackjack house edge and make counting harder.

Shooter

The player currently rolling the dice in craps. The role passes around the table.

Sic Bo

A dice game played with three dice in which players bet on totals and combinations. The Big and Small bets carry a house edge of about 2.78%, while many other bets on the layout are much higher.

Side Bet

An optional extra wager added to a main game, such as insurance in blackjack or the tie in baccarat. Side bets usually carry higher house edges than the main game.

Six-Line Bet

An inside roulette bet covering two neighboring rows, or six numbers, on the layout. It pays 5 to 1.

Six-to-Five Blackjack

A blackjack game that pays 6 to 5 for a natural instead of the traditional 3 to 2. The smaller payout adds about 1.4% to the house edge.

Soft 17 Rule

The house rule on whether the dealer must hit or stand on a soft 17. Tables where the dealer stands on soft 17 are better for players than tables where the dealer hits.

Soft Hand

A blackjack hand with an ace counted as 11, such as ace-6 for soft 17. It cannot bust on the next card because the ace can drop to 1.

Split

A blackjack option to separate a pair into two hands, each with a bet equal to the original. Basic strategy always splits aces and eights and never splits fives or tens.

Split Bet

An inside roulette bet on two numbers next to each other on the layout. It pays 17 to 1.

Sportsbook

A business that takes bets on sporting events. Like any bookmaker, it profits mainly from the margin built into its odds.

Spot

In keno, each number a player chooses. A 6-spot ticket means you picked six numbers, and the pay table depends on how many of them are drawn.

Stand

To keep your current blackjack hand and take no more cards.

Standard Deviation

A measure of how widely results spread around the average. For flat even-money bets, the standard deviation over n bets is roughly the bet size times the square root of n.

Straight

Five cards in sequence of mixed suits, such as 5-6-7-8-9. There are 10,200 straights among the 2,598,960 possible five-card hands.

Straight Flush

Five cards in sequence, all of the same suit. Excluding royal flushes, there are 36 possible straight flushes.

Straight-Up Bet

A roulette bet on a single number. It pays 35 to 1, and on a European wheel the chance of winning is 1 in 37.

Street Bet

An inside roulette bet on a row of three numbers. It pays 11 to 1.

Sucker Bet

An informal name for a wager with a notably high house edge, such as the baccarat tie bet or many one-roll craps bets.

Sunk Cost Fallacy

The urge to keep investing because of what you have already spent, even when continuing no longer makes sense. In gambling it often drives people to keep playing to justify earlier losses.

Surrender

A blackjack option to give up your hand and take back half your bet. With late surrender, basic strategy surrenders hard 16 against a dealer 9, 10 or ace, and hard 15 against a 10.

T

Table Limits

The minimum and maximum bets allowed at a table. Maximums protect the casino from very large swings and stop doubling systems like the Martingale from continuing indefinitely.

Texas Hold'em

The most widely played poker variant, in which each player gets two private cards and shares five community cards. Players make the best five-card hand from any combination of the seven.

Theoretical Loss (Theo)

The amount a player is expected to lose, calculated as average bet times decisions per hour times hours played times house edge. Casinos use it to rate players and decide comps.

Third Base

The last seat to act before the dealer at a blackjack table. Despite popular belief, the choices made in that seat do not change other players' expected results.

Three of a Kind

A poker hand with three cards of the same rank plus two unrelated cards. There are 54,912 such hands among 2,598,960 possibilities.

Ticket-In, Ticket-Out (TITO)

A system in which slot machines print paper vouchers instead of paying out coins and accept those vouchers as credits at other machines.

Tie Bet

A baccarat wager that the Banker and Player hands will finish level. At the common 8 to 1 payout the house edge is about 14.36%; at 9 to 1 it falls to about 4.84%.

Tilt

A state of frustration or emotional upset, often after a painful loss, that leads a player into reckless decisions. The idea applies to any gambling where emotions start driving the bets.

Time Limit

A cap on how long you will gamble in a session, set in advance and backed by an alarm or account setting. Since expected loss grows with time played, a time limit also works as a money limit.

True Count

In card counting, the running count divided by the estimated number of decks remaining. It shows how favorable the remaining cards are and guides bet sizing.

True Odds

The actual likelihood of an event expressed as odds, before any house margin. A single number on a European wheel has true odds of 36 to 1 but pays 35 to 1.

Turn

The fourth community card in Texas Hold'em, dealt after the betting round on the flop.

Two Pair

A poker hand with two different pairs plus a fifth card, such as two jacks and two fours. There are 123,552 such hands.

U

Unit

A standard bet size used to describe a betting plan, such as $10 per unit. Systems and bankroll guides are often written in units so they scale to any budget.

Upcard

The dealer's face-up card in blackjack. Basic strategy depends on it because it strongly predicts how often the dealer will bust.

V

Variance

A measure of how far results tend to spread from the expected value, equal to the standard deviation squared. High-variance games produce bigger swings in both directions.

Video Poker

A machine game based on five-card draw poker in which you choose which cards to hold. With a known pay table and optimal strategy its return can be calculated exactly, and a few rare versions exceed 100%.

Vig (Vigorish)

The commission or margin a bookmaker builds into its odds. On a standard −110/−110 line you risk $110 to win $100, which gives the bookmaker a margin of about 4.55% of balanced handle.

Virtual Reel

A software map that assigns many random-number positions to each displayed reel stop. It lets designers make some symbols far rarer than they look, including making blanks next to jackpot symbols unusually common.

Volatility

How a game's payouts are spread over time. Low-volatility slots pay small wins often, while high-volatility slots pay rarely but sometimes much bigger, even at the same RTP.

W

Whale

Industry slang for a player who bets extremely large amounts. A single whale's results can noticeably swing a casino's short-term revenue.

Wild Symbol

A slot symbol that substitutes for other symbols to complete winning combinations.

Win Goal

An optional target at which you stop and keep your winnings. Many people set aside part of any win so it does not get gambled back.

Y

Yo

Craps slang for eleven, used so it is not confused with seven. A one-roll bet on 11 that pays 15 to 1 carries a house edge of about 11.11%.

Z

Zero

The green pocket on a roulette wheel that is neither red nor black, odd nor even. It is the source of the house edge on a single-zero wheel.