Glossary
Betting & gambling glossary
Plain-English definitions of the betting, poker and casino terms behind the calculators — each one linked to the tool that puts it to work.
Accumulator (parlay)
Several bets combined into one, where all must win to pay out.
American odds (moneyline)
The US format: + shows profit on 100, − shows the stake needed to win 100.
Arbitrage (surebet)
Backing every outcome across bookmakers to lock in a guaranteed profit.
Asian handicap
A handicap with no draw, including quarter lines that split your stake.
Bankroll
The money set aside strictly for betting, separate from everything else.
Betting exchange
A marketplace where bettors back and lay against each other, not a bookmaker.
Bonus (deposit bonus)
Extra funds a book or casino grants, tied to wagering conditions.
Break-even percentage
The win rate a price needs just to stop losing money.
Closing line value (CLV)
Whether you beat the final odds the market settled on before kickoff.
Decimal odds
The European format: total return per unit staked, including the stake.
Drawdown
The peak-to-trough drop in your bankroll during a losing stretch.
Dutching
Splitting a stake across several selections to profit equally whichever wins.
Each-way
One bet in two parts: a win bet and a place bet at a fraction of the odds.
Edge
Your percentage advantage over the odds on offer.
Equity
Your share of the pot right now, equal to your chance of winning it.
Expected value (EV)
The average profit or loss a bet returns if it were repeated forever.
Flat betting
Staking the same amount on every bet regardless of confidence.
Fold equity
The extra value a bet gains from the chance your opponent folds.
Fractional odds
The UK format: profit relative to stake, written as a fraction.
Free bet
A promotional stake returned as winnings only — the stake itself is not.
Gambler's fallacy
The false belief that past independent results change what comes next.
Half Kelly
Staking half the Kelly-optimal fraction to cut the swings.
Handicap
A virtual head start or deficit applied to one side to level a market.
Hedging
Placing an opposing bet to lock in profit or cap a loss.
Hit rate (strike rate)
The percentage of your bets that win.
House edge
The casino's built-in mathematical advantage on a bet, as a percentage.
ICM (independent chip model)
Converts tournament chip stacks into real prize-money equity.
Implied odds
The extra money you expect to win later if your draw comes in.
Implied probability
The win chance that a set of odds corresponds to: 1 ÷ decimal odds.
Kelly criterion
A formula for the bet size that maximises long-term bankroll growth.
Lay bet
Betting on something not to happen, taking the role of the bookmaker.
Liability
What a lay bettor risks — the amount owed if the bet they laid wins.
Limit (account limiting)
A cap a bookmaker puts on how much you are allowed to stake.
Line shopping
Comparing the same bet across books and always taking the best price.
Martingale
Doubling your stake after every loss to recover it with one win.
Matched betting
Using a promotion plus an opposing lay to extract guaranteed value.
MDF (minimum defence frequency)
How often you must continue so that bluffing you is not automatically profitable.
Middling
Betting both sides of a line that moved, so both can win.
Outs
The unseen cards that improve your hand to a likely winner.
Overround
How much the implied probabilities of a market add up to above 100%.
Pot odds
The price you're being offered to call, as a ratio of pot to bet.
Provably fair
A crypto-casino scheme that lets players verify each result was not rigged.
Push
A tie that returns your stake — no win, no loss.
Rakeback
A share of the rake you have paid, returned to you by the poker room.
Risk of ruin
The probability of losing your whole bankroll given your edge and bet size.
ROI (return on investment)
Net profit as a percentage of the total amount you staked.
RTP (return to player)
The percentage of all wagers a game pays back over the long run.
Seed (server & client seed)
The inputs a provably fair game hashes to fix a result in advance.
Sharp
A winning, respected bettor whose money moves the market.
SPR (stack-to-pot ratio)
The effective stack divided by the size of the pot.
Standard deviation
A measure of how far results typically stray from their average.
Steam (steam move)
A sharp, sudden line move as respected money hits the market.
Tilt
Playing worse than you know how to because of emotion, usually after losses.
True odds
The real mathematical probability of an outcome, before any margin.
Unit
A standard bet size, expressed as a fixed percentage of the bankroll.
Value bet
A bet whose true chance of winning is higher than the odds imply.
Variance
How widely results swing around their expected value in the short run.
Vig (vigorish)
The bookmaker's built-in commission, baked into the odds of every market.
Void bet
A bet cancelled outright, with the stake returned.
Volatility
How a game's payouts are distributed: many small wins vs rare big ones.
Wagering requirement
How many times a bonus must be staked before it can be withdrawn.
Yield
Another name for betting ROI — profit divided by total stake.