Sports betting terms explained
Published on 22 August 2026
The vocabulary of sports betting mixes probability terms, anglicisms and operators' own expressions. Here are some of the important ones, defined simply. Terms related to the real cost of a bet link through to the detailed guides.
1X2
The main three-outcome market of a football match: home win (1), draw (X), away win (2). It is usually the best-priced market of a fixture, and therefore the one with the highest RTP.
Account limitation
A unilateral measure by which a bookmaker reduces the maximum stake allowed on a bettor's account. It mainly targets the (very rare) long-term winning players, users of arbitrage techniques (surebets) and profiles flagged as a risk to the operator's profitability.
Accumulator (parlay)
A bet combining several selections, whose odds multiply — and so do the margins. The RTP of an accumulator is the product of the RTPs of each selection: three selections at 95% give 85.7%, eight selections give 66.3%. It is structurally the most expensive bet type for bettors. See why accumulators are a gold mine for bookmakers.
Bankroll
The amount of money a bettor holds across the various bookmakers they are registered with.
Betting exchange
A platform where bettors face each other directly, the operator earning an explicit commission on winnings rather than a margin built into the odds. The cost is visible there, which does not automatically make it lower.
Bookmaker
An operator that offers odds and accepts bets. It charges no visible commission: its revenue is baked into the odds it offers, in the form of a margin. See how to calculate a bookmaker's margin.
Bookmaker's margin
The share of the stakes the operator keeps on average, expressed as a percentage. It is the exact complement of the RTP: margin = 100 − RTP. It varies with the competition, the market type and the timing. See how to calculate a bookmaker's margin.
Boosted odds
An odd temporarily increased by an operator for commercial purposes. It improves the RTP of the market concerned on a one-off basis.
Cash out
An option allowing a bet to be settled before the end of the event, for an amount offered by the operator. That amount carries an additional margin over the theoretical value of the position: convenience has a price.
Closing line
The final odd of a market, just before the event starts. It is regarded as the most accurate, since it incorporates all the information available to the bookmakers' pricing engines.
CLV (Closing Line Value)
The gap between the odd obtained at the time of the bet and the closing line. Consistently beating the closing odd is one of the rare serious indicators of a genuine edge over a bookmaker. An important nuance: securing a positive CLV long before kick-off is more demanding and far more complex, because early odds always carry wider margins.
Correct score
A bet on the precise result of a fixture. A market with a great many outcomes, generally among the highest-margin ones in the catalogue.
Double chance
A bet covering two of the three outcomes of a match (1X, 12 or X2). The odd is mechanically lower; the margin, however, is not necessarily smaller.
Dutching
Splitting a stake across several outcomes of the same market so as to obtain the same payout whichever one occurs. Useful for understanding the logic of implied probabilities, but with no effect on the market's margin.
Expected value
The average result expected from a bet repeated a large number of times. On a market where the RTP is below 100%, and short of a bookmaker pricing error allowing a value bet, expected value is systematically negative for bettors as a whole — it is the mathematical expression of the margin.
Free bet
A bet granted by the operator whose stake is not returned when it wins: a £100 free bet at odds of 2.00 returns only £100 of net profit. Its effective value is therefore well below its face amount.
Handicap
A fictional advantage or disadvantage given to a team to rebalance a lopsided match. The European handicap keeps three outcomes; the Asian handicap removes the draw, sometimes with fractional lines that split the stake.
Implied probability
The probability contained in an odd, obtained by inverting it: an odd of 2.50 corresponds to 1 ÷ 2.50 = 40%. The sum of the implied probabilities of all outcomes of a market always exceeds 100%; that excess is the margin. See what is the RTP of a sports bet.
Kelly criterion
A stake-sizing formula that allocates a fraction of the bankroll proportional to the estimated edge. It assumes knowing the true probability of an outcome — which nobody knows with certainty.
Live betting
A bet placed while the event is under way, on odds recalculated continuously. Margins there are generally wider than pre-match, as uncertainty and processing speed are both higher.
Odds
The numerical expression of the payout attached to an outcome. They contain both a probability estimate and the operator's margin. They are written in three main formats, depending notably on the bookmaker's region: decimal, fractional and American. See the three main odds formats.
Over / Under
A bet on whether a statistic exceeds a set threshold or not: number of goals, games, points. A two-outcome market, whose RTP is computed exactly like any other.
ROI (return on investment)
A profitability indicator computed by dividing net profit (or loss) by the total amount staked, expressed as a percentage.
Rollover (wagering requirements)
The number of times a bonus must be re-wagered before it can be withdrawn, often with a minimum odd and a deadline attached. It is one of the mechanisms that reduce the real value of a promotional offer.
RTP (Return To Player)
The share of the stakes a market gives back to bettors, on average. An RTP of 94% means that for every €100 staked, across all outcomes, the odds give back the equivalent of €94. It is the central notion of this site. See what is the RTP of a sports bet. A side note: in some countries the RTP is also framed by regulation — in France, for instance, the average annual RTP of licensed operators is capped at 85% by the national gambling authority.
Stake
The amount committed to a bet. With decimal odds, the total return displayed includes the stake; with fractional and American odds, the figures express net profit, stake excluded — a frequent source of confusion.
Surebet (arbitrage)
A situation where the odds of different operators on the same market allow every outcome to be covered with a guaranteed profit. It corresponds to an RTP above 100% and is generally rare and short-lived.
Value bet
A bet whose offered odd is higher than the fair odd corresponding to the true probability of the outcome. Identifying a value bet requires a better estimate of an event's true probability than the bookmakers have, which is very difficult. A low RTP makes the exercise almost impossible.
Variance
The dispersion of results around their average. It is what allows a short run to be profitable despite an unfavourable RTP — and what makes any conclusion drawn from a few dozen bets unreliable.
Welcome bonus
A commercial offer aimed at new registrants. Its real value is almost always lower than the headline amount: it is most often paid in free bets rather than real money, and comes with conditions. An RTP gap, by contrast, applies to every bet and never expires — which is why it matters far more over time. See the guide compare bookmakers by RTP rather than bonuses.