Sports Betting Glossary — Sports Betting Education | CapperU

Sports betting has its own language. This glossary defines the terms you'll encounter when reading lines, placing bets, or evaluating your own process.

Terms are grouped by topic — odds and probability, bet types, bankroll and edge, market movement, and results/jargon — because related concepts are more useful together than scattered alphabetically.

Definitions are kept short. Where a term has a dedicated CapperU guide, we link to it.

Odds and probability

American odds The US standard for displaying bet prices, using + and − signs. Negative odds (−150) indicate a favorite: you must risk that much to win $100. Positive odds (+130) indicate an underdog: a $100 bet wins that amount in profit.

Decimal odds Common in Europe and exchanges. The total payout including your stake, expressed as a multiplier. 2.50 means a $100 bet returns $250 total ($150 profit + $100 stake).

Fractional odds Common in the UK. Displayed as profit : stake. 5/2 means $5 profit for every $2 wagered.

Implied probability The win percentage suggested by the odds — what the price implies you need to win to break even. American odds formulas: negative odds |odds| ÷ (|odds| + 100); positive odds 100 ÷ (odds + 100). → Full guide

True probability Your estimate of how often an outcome will actually occur, based on your own analysis or model. The gap between true probability and implied probability is where edge lives — if you have any.

Overround The amount by which the sum of implied probabilities across a market exceeds 100%. It is the sportsbook's margin expressed in probability terms. A −110/−110 market has an overround of ~4.76%.

Vig (vigorish, juice) The sportsbook's built-in margin. It is embedded in the odds rather than charged as a separate fee. At −110/−110, the vig is the reason you need to win 52.38% of bets to break even, not 50%. → Full guide

Hold The expected profit the sportsbook keeps as a percentage of handle, based on the overround structure of the market. Related to vig but measured at the market level rather than the per-bet level.

No-vig probability An estimate of the market's "fair" price after removing the sportsbook margin. Calculated by normalizing each side's implied probability by the total overround. Useful as a baseline for comparison when you're building or evaluating a model.

Even money (+100) A price at which you risk the same as you stand to win in profit. Implies 50% break-even probability.

Edge The advantage you have over a bet — the difference between your estimated true probability and the implied probability in the odds. If your estimated probability exceeds the implied probability, the bet may have positive expected value. → EV guide

Break-even win rate The win percentage needed to not lose money at a given price. At −110: 52.38%. At −105: 51.22%. At +100: 50.00%. → Implied probability and break-even table

Common bet types

Moneyline A straight bet on who wins the game, with no spread involved. Favorites have negative moneyline odds; underdogs have positive. The payout reflects the implied probability of each side winning outright.

Point spread (spread, ATS) A handicap that levels an uneven matchup. The favorite gives points (−7.5) and must win by more than that to cover; the underdog gets points (+7.5) and can lose by less — or win outright — to cover. Most spreads are priced at or near −110 on each side.

Total (over/under) A bet on the combined score of both teams. The sportsbook sets a number; you bet whether the actual total will be higher (over) or lower (under). Most totals open at −110 on each side.

Run line The baseball version of a point spread. Standard run line is typically −1.5 (favorite) / +1.5 (underdog) with adjusted juice, rather than fixed at −110.

Puck line The hockey equivalent of a run line. Standard puck line is typically −1.5 / +1.5.

First 5 innings (F5) A bet that settles based only on the first five innings — before the bullpen takes over. Useful for isolating starting pitcher matchups from bullpen variance.

Team total A bet on one team's individual score, independent of the opposing team. Useful when you have a view on one offense without a strong opinion about the other.

Prop bet (proposition bet) A bet on a specific event within a game that doesn't directly determine the final result. Examples: pitcher strikeouts over/under, a batter's total bases, whether a team scores in the first inning. Props often carry higher vig than main markets. → MLB Props Guide

Parlay A single ticket combining two or more bets, all of which must win for the parlay to cash. One loss kills the ticket. Parlays offer higher payouts but compound risk — and compound vig.

Same-game parlay (SGP) A parlay where all legs come from the same game. Most sportsbooks build extra margin into SGP pricing because of the correlated nature of the legs.

Teaser A type of parlay where you move the spread or total in your favor across multiple games, in exchange for reduced odds. You pick up points at the cost of a lower payout.

Futures A bet on an outcome that won't be decided until much later — championship winners, award winners, season-long totals. Futures boards typically carry high overround (sometimes 130–140% combined implied probability).

Alternate line A non-standard spread or total offered at a different price. Alternate +2.5 may be available at −200 when the main spread is −1. Alternate totals are common for totals shopping.

Hedge Betting the opposite side of an existing wager to lock in profit or limit loss, usually after circumstances have changed in your favor.

Arbitrage Betting all outcomes of an event across different books to guarantee profit regardless of result, by exploiting pricing discrepancies. True arbitrage is rare and books actively work to close it.

Bankroll and value terms

Bankroll The total amount of money set aside exclusively for betting. Proper bankroll management prevents catastrophic loss and is the prerequisite for any sizing strategy to work.

Unit A standard bet size expressed as a fraction of bankroll. A common convention is 1 unit = 1–2% of bankroll. Using units instead of dollar amounts makes record-keeping and comparison consistent across bankroll sizes.

Flat staking Betting the same number of units regardless of your edge or confidence level. Simple, disciplined, easy to track. The right default until you have a validated probability model.

Expected value (EV) The average profit or loss per bet if you could repeat it many times at the same odds with the same true probability. Positive EV (+EV) means the bet is profitable in expectation. Negative EV (−EV) means it isn't. → Full guide

Kelly Criterion A formula for sizing bets as a fraction of bankroll, proportional to your estimated edge. Full Kelly is mathematically optimal under ideal assumptions but prone to large drawdowns when probability estimates are wrong. Most practical applications use fractional Kelly. → Full guide

Risk of ruin The probability of losing your entire bankroll before a strategy has a chance to show its edge. Drives the case for unit sizing discipline and bankroll cushion. → Bankroll Management guide

ROI (return on investment) Total profit divided by total amount wagered, expressed as a percentage. A 5% ROI means you earn $5 profit per $100 wagered on average.

Variance The natural spread of results around the expected value. Even a correctly sized +EV bet will produce losing stretches. Variance is why short-term records are unreliable signals of process quality.

Market movement and pricing terms

Opening line The first price a sportsbook posts for a market. Usually posted well before game time, often with lower limits while the book gauges market interest and information.

Closing line The final odds available just before the event starts. Generally the most information-rich price, because all publicly known factors have had a chance to be priced in. → How CLV uses the closing line

Closing line value (CLV) The difference between the odds you bet at and the odds at closing. Positive CLV means you got a better price than the market's final number. A useful process metric — but not a guarantee of profit, and less meaningful in low-liquidity markets. → Full guide

Line movement Changes in a line from open to close. Caused by new information (injuries, lineup news, weather) or betting volume. Lines can move the number, the price (juice), or both.

Steam move A rapid, coordinated line move caused by a surge of sharp money coming in at multiple books simultaneously. A steam move often causes multiple books to update quickly.

Sharp money Bets from professional or sophisticated bettors whose action books take seriously. Books track sharp action because it often reflects real information or model-based pricing.

Square money (public betting) Bets from casual or recreational bettors. Tends to go toward popular teams, big favorites, and overs. Books build pricing that accounts for expected square-side demand.

Consensus line An average or aggregate line across multiple sportsbooks. Outlier prices relative to the consensus can represent value — or can indicate a pricing error at one book.

Limit The maximum bet a sportsbook accepts on a given market. Limits vary by book, market type, and the bettor's account history. Sharp bettors are often limited or restricted.

Off the board A market that has been temporarily removed — no bets accepted. Common causes: injury news, lineup uncertainty, late news the book needs time to evaluate.

Outcomes and settlement terms

Action Having a live bet on an event. "No action" typically means a bet was voided — usually because a listed player (like a starting pitcher) didn't participate.

Cover In spread betting, meeting the required margin. A −7.5 favorite covers by winning by 8 or more. A +7.5 underdog covers by losing by 7 or less — or winning outright.

Push A tie against the spread or total. Stake is returned; no win, no loss. Happens when the final margin equals an integer spread (e.g., winning by exactly 7 on a −7 spread).

Void A bet that is canceled, usually because a necessary condition wasn't met (listed pitcher didn't start, game was suspended). Stake is returned.

ATS (against the spread) A way of expressing a team's record when covering the point spread, as opposed to their straight-up win-loss record.

Hook A half-point in the spread or total (e.g., 7.5 instead of 7). Eliminates the possibility of a push on common key numbers.

People and jargon

Sharp A professional or sophisticated bettor whose action moves lines. Books manage exposure from sharp accounts more carefully than from recreational players.

Square A casual or recreational bettor. Not a pejorative — just a term to distinguish betting behavior patterns.

Chalk Betting the favorite. "Taking the chalk" means siding with the heavily favored team at any given price.

Fade Betting against something. To "fade the public" means betting the opposite of where most recreational money is going.

Handicapper A person who analyzes games and produces picks. Can refer to a professional analyst, a model, or a paid service.

Handle The total amount wagered on an event or across a time period. Not the same as profit — it's gross intake.

Book / bookmaker The entity setting odds and accepting bets. Can refer to a sportsbook as a business or to the process of setting lines.

Tout A person or service selling picks — often using exaggerated win rate claims, pressure tactics, and fabricated "guaranteed" plays. A tout site is the opposite of a research-first approach.

Start researching

Put the vocabulary to work on today's MLB markets:

This glossary links throughout to deeper CapperU guides. Start with How Betting Odds Work if you're new, or jump to Expected Value if you want the core math.