60+ terms covering betting math (no-vig, devig, CLV, overround), market structure (sharp vs square, arbitrage, middling, alt-lines), and API integration (rate limits, idempotency keys, WebSocket, SSE). Includes schema.org DefinedTerm markup so AI search and Google rich snippets can quote individual definitions.
A sportsbook price with the bookmaker's overround (vig) mathematically stripped out, leaving the implied fair probability before commission. Used as the fair-value reference in +EV scanning. See no-vig CLV explained.
Devig
The process of normalizing the two sides of a two-way market so their implied probabilities sum to 1.0, removing the bookmaker's hold. Mathematically: p_no_vig = p_implied / (p_home_implied + p_away_implied).
Vig (Juice)
The bookmaker's commission embedded in the prices. The amount by which the sum of implied probabilities exceeds 1.0. Standard US sportsbook vig on a moneyline is ~4.76% (the gap from -110/-110 to 50/50).
Overround
Synonym for vig. The percentage by which implied probabilities sum past 100%. A 2-way market priced at -110/-110 has 104.76% overround, or 4.76% vig.
Hold
The bookmaker's expected profit margin, computed as overround divided by the sum of all implied probabilities. Distinct from vig only on multi-way markets where the math differs.
Closing Line Value (CLV)
The difference between the price you took on a bet and the closing price of the same market. Positive CLV is the strongest single correlate of long-run betting profitability. See closing-line snapshot conventions.
No-vig CLV
Closing-line value computed against the sharp book's devigged closing probability rather than the vigged closing price. The professional grading convention. Avoids double-counting the vig.
Implied probability
The probability of an outcome that's implied by the offered odds. For American odds: positive prices use 100/(price+100); negative prices use |price|/(|price|+100).
Implied sum
The sum of implied probabilities across all sides of a market. For arbitrage opportunities, implied sum < 1.0. See /arbs.
Kelly criterion
A bet-sizing formula that scales stake to the bettor's perceived edge and bankroll, theoretically maximizing long-run logarithmic growth. fraction = (bp - q) / b where p is win prob, q is lose prob, b is decimal odds minus 1.
Markets & bet types
Moneyline (h2h)
A bet on which team wins outright, with no point spread. Often abbreviated ML or h2h (head-to-head).
Point spread
A handicap that the favored team must cover. -3.5 means the favorite must win by 4+; +3.5 means the underdog can lose by up to 3 and still cover.
Total (Over/Under)
A bet on whether the combined score will be over or under a stated number. Also called the OU.
Player prop
A bet on an individual player's statistical performance (passing yards, points, rebounds, etc.) rather than on the game outcome.
Alt-line
An alternate version of the main spread or total at a different number, with adjusted prices. Books expose alt-lines at every half-point increment.
Same-game parlay (SGP)
A multi-leg bet where all legs are from the same game. Pricing accounts for correlation between legs. Live demo at /sgp.
Parlay
A multi-leg bet where every leg must win. Payout multiplies leg odds (independent or correlated).
Teaser
A multi-leg parlay where the spread or total is shifted in the bettor's favor by a fixed amount, at the cost of reduced payout per leg.
Round-robin
A bet structure that places parlays on every combination of N legs at a given size.
Futures (Outrights)
A bet on a long-term outcome like a championship winner. Settled at season end. Soccer and golf often call these "outrights."
The US-standard odds format. Negative numbers (-150) show how much you'd risk to win $100; positive (+130) show how much you'd win on a $100 stake.
Decimal odds
European-standard odds format. The number is the total payout per $1 staked, including the original stake. +130 American = 2.30 decimal.
Fractional odds
UK-standard odds format. A 13/10 fractional bet returns $13 profit per $10 staked.
Dime line
A two-sided market with a 10-cent vig (-105/-105 or similar). Pinnacle is famous for dime lines on most markets.
Reduced juice
A promotional price with lower vig than standard, e.g. -105/-105 instead of the usual -110/-110.
Closing line
The price posted by the sharp book in the final seconds before the market is removed (typically at event commence_time). The reference for CLV grading.
Best line
The most favorable price for a given side across all available books. Best-line shopping is a free edge for any disciplined bettor.
Line shopping
The practice of comparing prices across multiple sportsbooks before placing a bet and taking the best available.
Strategy
Positive EV (+EV)
A bet where your estimated win probability exceeds the implied probability of the price taken. Long-run profitable; not necessarily on the individual bet. See /ev and reading +EV outputs honestly.
Arbitrage (Arb)
A bet structure across two books where the sum of best-available implied probabilities is below 1.0, locking a guaranteed profit. See /arbs.
Middle (Middling)
A bet structure where two same-market positions at different lines can both win if the final result lands between them. See /middles.
Hedge
A second bet placed to reduce or eliminate exposure on a prior bet, typically locking in a profit or limiting a loss.
Steam move
A line move triggered when multiple books shift in the same direction within seconds, indicating coordinated sharp action.
Correlated parlay
A parlay where the outcomes of the legs are statistically dependent. Same-game parlays apply correlation adjustments.
Books & exchanges
Sharp book
A sportsbook (Pinnacle, Circa, Bookmaker.eu, BetCRIS) that takes high-limit action from informed bettors and continuously reshapes lines in response. Sharp prices are the public proxy for fair value.
Square book
A retail-focused sportsbook (DraftKings, FanDuel, BetMGM) that takes most action from recreational bettors and models prices to balance entertainment and profit.
Sharp anchor
The sportsbook used as the reference for fair-value computations. Pinnacle is the most common anchor for public +EV scanners.
Soft book
A retail sportsbook whose prices lag the sharp anchor. Soft books often have promotional odds and slower line moves, creating +EV opportunities.
Exchange
A peer-to-peer betting marketplace where users back and lay outcomes against each other rather than betting against the house. Examples: Smarkets, Matchbook, Betfair, ProphetX.
Back
On an exchange: betting FOR an outcome to occur. The default position on retail sportsbooks.
Lay
On an exchange: betting AGAINST an outcome (effectively becoming the bookmaker for that bet).
Prediction market
A market where contracts pay out based on real-world event outcomes. Examples: Kalshi, Polymarket. Contracts trade like securities.
Operations
Limit
The maximum stake a sportsbook will accept on a given market from a given account. Sharp accounts get higher limits; flagged-for-value accounts get reduced limits.
Exposure
A book's total liability on a given outcome. Books move lines to manage exposure, not just to forecast probability.
Action
The volume of betting handle on a given side. 'Sharp action' is large bets from informed accounts; 'public action' is many small bets.
Handle
The total dollars wagered on a given event, market, or sportsbook over a period.
Push
A bet that lands exactly on the line and is graded as a tie. Stake is returned.
Cover
To beat the point spread. 'The favorite covered' means it won by more than the spread number.
Stake
The amount risked on a bet.
Market suspension
A temporary state where a live market is offline because the book's risk engine cannot price it (during plays, injuries, reviews). Prices return when the book resumes.
The maximum number of API requests allowed per time window. Sportsbook APIs return HTTP 429 with a Retry-After header when the limit is hit.
WebSocket
A bidirectional connection protocol that allows the server to push updates without polling. Used for sub-second odds streaming. See /docs/websocket and the live demo at /ws-demo.
SSE (Server-Sent Events)
A unidirectional server-to-client streaming protocol over plain HTTP. Lighter than WebSocket; commonly used as a fallback.
Idempotency key
A unique per-request identifier sent in the Idempotency-Key header. The server returns the same response for any retry with the same key, making writes safe to retry.
Retry-After
An HTTP response header indicating how many seconds the client should wait before retrying. Returned on 429 and some 5xx responses.
Event ID
A stable identifier for a sporting event, generated by the aggregator from (game_date, home_team, away_team) or upstream IDs where available.
Market key
A canonical identifier for a betting market type, e.g. h2h, spreads, totals, player_points. Full catalog at /v1/meta/markets.
Commence time
The scheduled start timestamp of an event, ISO-8601 in UTC. Used as the canonical pre-game cutoff.
Devig pair
Two opposing prices that, taken together, can be devigged into a fair-probability pair. Both sides must exist for the devig to be valid.