Glossary
The vocabulary of cross-venue pricing, defined precisely and with a worked example where one helps. Every term links to the pages where we measure it.
AI-matched pair
A cross-venue market pair that an automated reviewer judged to be the same question, shown with the reviewer's confidence score.
American odds
The US sportsbook price format: negative numbers show the risk to win $100, positive numbers show the win on a $100 risk.
Annualized edge
An arbitrage's net edge divided by the fraction of a year until the contracts resolve — the return on capital locked up, not just the headline percentage.
Arbitrage (betting & prediction markets)
Backing every outcome of the same event across two or more venues at prices that add to less than the payout, so the same amount comes back whichever way it resolves.
Closing line value (CLV)
How much better the price you took was than the market's final price before the event — the standard measure of a bettor's edge.
Decimal odds
Total return per unit staked, including the stake: 2.10 returns $2.10 for every $1 bet, implying a 47.6% probability.
Dutching
Splitting a total stake across all outcomes in proportion to their prices so every outcome returns the same amount.
Expected value (+EV)
The average profit of a bet if it were repeated many times: probability of winning × payout minus probability of losing × stake.
Gross edge
The raw pricing gap before fees and before walking the order book — the number most 'free money' screenshots show.
H2H (head-to-head / moneyline)
A two-way market on which side wins outright, with no point spread — the sportsbook term is moneyline, the odds-feed key is h2h.
Hold (sportsbook hold percentage)
The share of total handle a book expects to keep on balanced action: overround divided by the sum of implied probabilities.
Implied probability
The probability a price implies if it were fair: 1 / decimal odds, or the contract price for a prediction market that pays $1.
Legging (getting legged)
Filling one side of an arbitrage and then failing to fill the other at the needed price, leaving an unhedged position.
Line shopping
Comparing the same bet across several books and taking the best price — the manual version of what a scanner automates.
Maker fee / maker rebate
What a venue charges (or pays) when your resting limit order is filled by someone else — $0 on Polymarket, $0 on most Kalshi series.
Middle (middling)
Betting both sides of a spread or total at different lines so that a result landing between them wins both bets, while any other result loses only the vig.
Moneyline
The sportsbook name for the head-to-head market: a bet on which side wins, priced in American odds with no spread.
Net edge
Profit as a percentage of total money put in, after every venue fee, at a size the books can actually fill.
No-vig odds (fair odds, devigged odds)
A book's prices with the margin removed, so the implied probabilities sum to exactly 100% — the book's actual estimate of the outcome.
Order book depth
How many contracts are available at each price level — the quantity you can actually fill, which is usually far less than the top quote suggests.
Point spread
A handicap market: the favorite must win by more than the spread, the underdog can lose by less than it, and both sides are usually priced near −110.
Pre-game vs in-play lines
Pre-game lines are set before the event and move slowly; in-play lines reprice every few seconds during it.
Prediction market
An exchange where contracts on real-world events trade between 0 and $1 and pay $1 if the event happens — the price is the crowd's probability.
Resolution criteria
The exact rules a prediction-market contract uses to settle — the fine print that decides whether two venues' 'same' market really is the same.
Sharp book vs soft book
A sharp book posts low-margin, quickly-corrected prices used as a reference; a soft book has higher margins and slower lines that lag the market.
Slippage
The difference between the price you saw and the average price you actually filled at, caused by thin depth or the market moving while you act.
Steam (steam move)
A sudden, market-wide line move driven by sharp money, which books copy within seconds to minutes.
Surebet
European term for a sports arbitrage: a set of bets across bookmakers covering every outcome with a locked-in return.
Taker fee (prediction markets)
The fee a prediction market charges when your order fills against resting liquidity — Kalshi and Polymarket both charge takers, scaled by price × (1 − price).
Total (over/under)
A market on the combined score of both teams: over the line or under it, each side priced separately.
Vig (vigorish, juice, overround, hold)
The margin a sportsbook builds into its prices: the amount by which the implied probabilities of all outcomes exceed 100%.