Reference · Glossary

Every sports betting term, defined plainly.

No jargon hand-waving. Each definition tells you what the word means, how to use it, and where the math hides.

Terms: 104
Categories: 8
Updated: 2026
License: Open

A

Action: A wager that has been placed and is live on a game or market. 'Having action' on a game means a sportsbook has accepted your bet and the outcome will determine whether you win or lose. Some markets - such as 'action' pitcher rules in MLB - settle regardless of starting-pitcher changes, while 'listed pitcher' bets are voided if either named starter is scratched.
Against the Spread (ATS): A team's record relative to the point spread rather than the straight-up result. A 9–3 NFL team can be 5–7 ATS if they routinely fail to cover as heavy favorites. ATS records over a full season are a more useful measure of how a team performs relative to market expectations than win-loss alone, though even a 16-game NFL sample is too small to draw strong predictive conclusions from.
Alternate Line: A spread or total moved off the main number at adjusted odds - e.g. buying down from -7 to -5.5 at -200, or buying up from +3 to +6.5 at +180. Alternate lines are useful for capturing specific value around key numbers, but the implied vig on alt lines is often higher than the main market, so each move should be evaluated for true cost.
American Odds: The +/- price format used in the US. Positive numbers (e.g. +200) show the profit on a $100 stake - $200 profit at +200. Negative numbers (e.g. -150) show how much you must stake to win $100 in profit. Implied probability: |odds| / (|odds| + 100) for negatives, 100 / (odds + 100) for positives. Standard US spreads and totals are priced near -110 on both sides for a theoretical hold of about 4.76%.
Arbitrage: Betting all outcomes of an event at different books to lock in a small risk-free return when prices misalign. True arbs typically yield 0.5%–2% and are rare on major US markets because sharp books reprice within seconds. Risks include voided bets, account limiting, palpable error rule-offs, and stake mis-sizing - arbitrage is not the consequence-free strategy it is often marketed as.
Asian Handicap: A soccer market that removes the draw by splitting handicaps into quarters and halves (-0.25, -0.75, etc.). A -0.25 bet wins fully if the team wins, pushes half the stake if the team draws. Common in European and Asian books; widely used by sharp soccer bettors because the structure produces low-hold two-sided pricing similar to point spreads.

B

Backdoor Cover: Late-game scoring that flips an Against-the-Spread result without affecting the actual winner - e.g. a meaningless touchdown in garbage time that pushes the dog over the number. Backdoor covers are a textbook example of why outcome bias is dangerous: a bet that won via backdoor was no smarter than one that lost by the same margin.
Bad Beat: A bet that loses in an unusually painful way - late lateral touchdowns, walk-off home runs that flip the run line, missed extra points that push instead of cover. Bad beats are statistically inevitable over a large bet sample and should not change a bettor's process. The opposite (a good beat) happens with equal frequency but is rarely complained about.
Bankroll: The total amount of money set aside exclusively for betting - never money required for living expenses, rent, or debt repayment. A disciplined bettor treats the bankroll as a closed system: deposits and withdrawals are tracked, and bet sizing (units, Kelly) is calculated as a percentage of current bankroll. A typical unit is 1%–2% of bankroll for flat bettors.
Beard: Someone who places bets on behalf of another bettor, typically to disguise sharp action from a sportsbook that would otherwise refuse or limit the original bettor. Common at retail counters and with limited accounts. Use of beards is restricted or prohibited by most regulated US sportsbooks under know-your-customer (KYC) rules.
Buying Points: Paying worse odds in exchange for a more favorable point spread or total - e.g. moving an NFL spread from -3 to -2.5 at a higher price. Buying through a key number (3 or 7 in the NFL) carries the largest implied value; buying off non-key numbers is usually -EV at standard half-point pricing.

C

Cash Out: A sportsbook offer to settle an open bet early for a price below its potential payout. Cash-out prices include a built-in margin (often 5%–15% above fair value) that makes them almost always -EV vs letting the bet run. The bettor pays for psychological certainty; the book sells it at a markup.
Chalk: The favorite - the side most heavily bet by the public, especially when the favorite is a popular team or large market. 'Going chalk' on a slate means betting all favorites. Long-term, public chalk parlays carry a meaningful negative ROI because each leg compounds the vig the bettor is paying.
Circled Game: A game with reduced betting limits, often due to injury uncertainty, weather, or referee assignment news. Circled status reflects sportsbook uncertainty about the line and is a signal the book itself does not trust its number - for analytical bettors, a circled game can offer rare value if their own information is sharper than the book's.
Closing Line: The final odds offered before a market closes at game time. Considered the most efficient price the market produces, because the largest volume of sharp and informed action has been absorbed. Academic studies of sports markets (Pinnacle data, betting-market papers) repeatedly find the closing line is the single best predictor of actual outcome probability.
Closing Line Value (CLV): The difference between the price you bet and the closing line. A bet placed at -105 that closes at -115 captured about half a point of CLV. Consistent positive CLV is the strongest known leading indicator of long-term betting profitability - usable in dozens of bets, where bottom-line ROI takes hundreds or thousands. If you cannot beat the close, you do not have an edge.
Correlated Parlay: A parlay whose legs are statistically linked - e.g. a team's moneyline and over, or a starting pitcher under and his team's moneyline. Same-game parlays are the most common modern form; books reprice them aggressively to strip out correlation premium, typically taking 15%–25% effective hold compared to ~5% on a straight bet.
Cover: When a team beats the spread - wins by more than the favorite is laying, or loses by less than the underdog is getting. A -7 favorite covers by winning by 8 or more; a +3 underdog covers by losing by fewer than 3 or winning outright. A result that lands exactly on the spread is a push, not a cover.

D

Dead Heat: A tie for a finishing position, leading to a proportional stake reduction on certain prop or futures markets (golf top-5 finishes, NFL player props with multiple tied players). Standard dead-heat rules pay out at (stake × odds) ÷ number of tied competitors - a known source of hidden -EV in props with thin fields.
Dead Money: Stake locked into a losing position that cannot be recovered without an unlikely sequence of outcomes. The phrase also applies to futures tickets that are mathematically eliminated mid-season. Recognizing dead money quickly is a discipline check - chasing dead money with hedges or doubles is a common path to bankroll damage.
Decimal Odds: European-format odds expressed as a multiplier that includes your stake. A $10 stake at 2.50 returns $25 total ($15 profit + $10 stake). Implied probability is simply 1 / decimal, making it the cleanest format for math. Used by Pinnacle, most European books, and virtually every quantitative betting tool - including this site's calculators.
Dime Line: A baseball moneyline where the gap between favorite and underdog is only 10 cents (e.g. -120 / +110), giving a low theoretical hold around 2%–2.5%. Dime lines were standard at sharp baseball books for decades; many modern US sportsbooks now post 20-cent or wider lines on MLB, materially raising the long-run cost to bettors.
Dog: Shortened term for underdog - the side expected to lose straight up, indicated by a plus sign in American odds. Public sentiment historically leans toward favorites, and structurally-priced home-underdog spots in the NFL have shown modest profitability over multi-decade samples, though the edge is small and decaying as markets sharpen.
Dollar Line: A baseball moneyline market with a 20-cent spread between favorite and dog (e.g. -130 / +110) - materially higher vig than a dime line. The hold on a 20-cent line is roughly 4%–5% vs ~2% on a dime line, meaning a recreational MLB bettor pays double the structural cost over a season.
Drift: When a price gets longer (worse for favorite, better for dog) over time, typically reflecting fading support or sharp action on the underdog. The opposite of steam in/short. Tracking which sides drift vs which steam in is a basic input for line-movement analysis.

E

Edge: The amount by which your estimated true probability exceeds the market's implied probability after vig is stripped. Stated as expected ROI per bet: edge = (your_p × decimal_odds) − 1. A typical professional sports bettor operates with edges of 1%–3% per bet - anything claimed above 5% sustained over thousands of bets is extraordinary and should be scrutinized.
EV+ / +EV: Shorthand for a positive expected value bet - one where your true win probability exceeds the implied probability of the price by more than the vig. A bet at +110 (implied 47.6%) that you estimate at 52% true probability is +EV by approximately 9.2% per $1 staked. Building a +EV process is the only durable path to long-term betting profit.
Even Money: A bet that pays exactly 1:1 - +100 in American odds, 2.00 in decimal, 1/1 fractional, 50% implied probability. The cleanest reference point for thinking about bet sizing: at even money, a 51% true win rate is +EV and a 49% true win rate is -EV.
Expected Value (EV): The average outcome of a bet over the long run, computed as (p × profit) − ((1 − p) × stake), where p is your estimated true win probability. Positive EV bets are profitable in expectation even when they lose individually; negative EV bets are losing propositions even when they win. EV is the only mathematically coherent way to judge whether a bet was 'good' independent of the result.
Exposure: The total amount at risk across all active bets. A bettor with $200 across three open NBA games has $200 of exposure. Disciplined bettors cap total exposure as a percentage of bankroll (commonly 10%–25%) to limit risk of ruin if multiple correlated outcomes go against them on the same slate.

F

Favorite: The team or outcome priced as more likely to win, indicated by a minus sign in American odds (e.g. -150) and a decimal below 2.00. Favorites carry lower payouts because they are expected to win more often; over the long run, betting favorites vs underdogs produces similar ROI when adjusted for vig - neither side is structurally profitable.
First Half Bet: A wager limited to the result, total, or spread of the first half of a game. 1H markets often respond more sensitively to pace and early game-script than full-game markets, and can be useful for bettors with specific in-game expectations (e.g. a slow-starting team that historically improves in the second half).
Fractional Odds: UK and Irish format showing odds as a ratio (e.g. 5/2). The first number is profit; the second is stake - so 5/2 returns $5 profit per $2 risked. Convert to decimal by dividing and adding 1: 5/2 → 2.50 + 1 = 3.50. Implied probability is denominator / (numerator + denominator) - 5/2 → 2/7 ≈ 28.6%.
Futures: A long-term wager on the outcome of an event in the future - Super Bowl winner, season MVP, World Series, World Cup. Futures markets often carry very high hold (10%–30%+) because pricing many outcomes leaves room for large overround. Capital is also locked up for months, so the implied cost of carry should be considered against alternative bankroll uses.

G

Grand Salami: A bet on the combined total of goals or runs scored across every game on a sport's slate that day. Available primarily in NHL and MLB. Because the bet is correlated to a single weather day or umpire pool, it can offer arbitrage and variance-trading opportunities not present in individual game totals.

H

Half Time Bet: A wager that only considers what happens after halftime. Spreads and totals are reset based on the score at the half. 2H markets often carry slightly higher hold than full-game markets but can offer value when first-half script has visibly distorted lines (e.g. one team building a big lead, key player foul trouble).
Handicap: Another term for the point spread - a virtual head-start applied to one side to level the market. Common globally outside the US, and the standard format in soccer (Asian Handicap) and rugby. A +1.5 handicap adds 1.5 goals to that side's final score for settlement purposes.
Handle: The total amount of money wagered on a market, by a sportsbook, or across an entire industry. State regulators (NJ DGE, NV GCB, PA PGCB, NY GC) publish monthly handle reports that show how much was wagered, the sportsbook's hold percentage, and revenue. US sports betting handle exceeded $100 billion annually starting in 2023.
Hedge: Placing a wager on the opposite side of an open bet to lock in profit or limit downside risk. Hedging always costs EV vs letting the original bet run, but it can be the right bankroll decision when a futures ticket has appreciated to a significant fraction of total bankroll and the certainty of locked-in profit outweighs the EV given up.
Hedging: Placing a second bet on the opposite outcome to reduce risk or lock in profit on an open position. Common with futures - e.g. hedging a long Super Bowl ticket once the team makes the championship. Hedging always costs EV vs letting the original bet run, but it can be rational for bankroll-management reasons when a single ticket is a large fraction of bankroll.
Hold: The percentage of total handle a sportsbook keeps as profit on a given market. Theoretical hold on a standard -110/-110 spread is 4.76%; on a dime line in baseball it is around 2%; on heavy parlay markets and certain props it can exceed 20%. Realized hold (true hold) often differs from theoretical due to bet distribution and outcome variance.
Hook: The half-point in a spread or total (e.g. -3.5 has 'the hook'). The hook matters disproportionately around key numbers - moving from -3 to -3.5 in the NFL is far more valuable than moving from -4 to -4.5, because 3 is the single most common margin of victory in pro football.
House Edge: The structural advantage a sportsbook holds due to vig and price asymmetry - the long-run profit they expect per dollar wagered. On a standard -110/-110 spread the house edge is ~4.76% per bet; on parlays it compounds to 25%+ effective on common 4-5 leg tickets. Reducing the house edge you pay (line shopping, reduced juice, avoiding parlays) is mechanically equivalent to adding edge.

I

Implied Probability: The break-even win rate that a price quotes, derived directly from the odds: 1 / decimal, |odds| / (|odds| + 100) for negative American, 100 / (odds + 100) for positive American. On a two-sided market the two implied probabilities sum to more than 100% - the overage is the sportsbook's hold. No-vig (true) probability divides each side by the sum to normalize back to 100%.
In-Play / Live Betting: Wagers placed during a game while the action is ongoing. Live odds update second by second based on score, time, possession, and the book's pricing model. Live markets often carry higher hold than pre-game (5%–10% on spreads and totals) but can offer value when a model misprices a moment - e.g. a fluky early goal, a brief injury scare, or a clock-management spot.

J

Juice / Vig: The commission built into the odds that gives the sportsbook its margin. On a standard -110/-110 market the vig is ~4.76%. Vig is the single most important cost a bettor pays - reducing average vig from 4.76% (-110) to 2.4% (-105) doubles a marginal bettor's edge. Shopping multiple books to find the best price on every bet is the highest-ROI habit a recreational bettor can adopt.

K

Kelly Criterion: A formula for sizing bets in proportion to your perceived edge and the odds offered: f = (bp − q) / b, where b = decimal odds − 1, p = true win probability, q = 1 − p. Maximizes long-term geometric bankroll growth. In practice, fractional Kelly (¼ or ½) is standard among professionals because full Kelly is highly sensitive to overestimating edge and produces large drawdowns.
Key Number: Common margins of victory that disproportionately affect spread bets. In the NFL the most frequent margins are 3 and 7, followed by 10, 6, 14, and 4 - a -3 favorite wins exactly by 3 roughly 9% of the time, the highest single-number push rate in major US sports. NCAA basketball key numbers cluster at 4, 5, and 8; MLB run lines and NHL goal lines cluster at 1.

L

Layoff: When a sportsbook bets at another sportsbook to reduce its own exposure on an imbalanced market. Layoff betting is one reason apparent 'sharp' action at a small book can sometimes simply be a larger book balancing its book - a reminder that line movement always has multiple plausible explanations.
Limit: The maximum stake a sportsbook will accept on a given market. Sharp books (Pinnacle, Circa) post relatively high limits and adjust their lines when a sharp bet hits the limit. Soft books post low limits and selectively limit individual winning accounts rather than moving their line - a structural reason most retail US books are not sharp.
Line: The current price, spread, or total offered on a market. Lines move from open to close in response to bets placed (book balancing exposure) and new information (injury, weather, sharp action). The opening line is a sportsbook's first estimate; the closing line is the market's collective estimate after thousands of inputs.
Line Movement: Any change in the price or spread from when the market opens to when it closes. Distinguishing money-driven moves (balancing) from information-driven moves (sharp action, news) requires looking at bet count and dollar handle together - direction alone is not enough. Reverse line movement is the canonical sharp signal.
Listed Pitcher: A baseball wager that is only valid if the named starting pitchers actually pitch - the bet is voided and stake returned if either is scratched. The opposite is 'action,' which stands regardless of starter changes (typically at adjusted odds). Listed pitcher protection is critical when betting starter-driven props or totals.
Live Line: The real-time, in-game price offered while play is ongoing. Live lines update continuously based on game state, time remaining, and the book's pricing model. Built-in vig on live markets is typically higher than pre-game (5%–10% on spreads and totals) because of model uncertainty around fast-moving information.
Live Odds: The current real-time price of a market, often shifting second by second during a game as the book's model reacts to score, time, and field position. Live markets are run by automated trading systems with built-in margins that protect against rapid information arrival, which is why live hold is typically higher than pre-game hold.
Lock: A bet described as 'guaranteed' to win. No such thing exists in sports betting. A 90% favorite still loses 1 in 10 times - a four-leg 'lock' parlay of 90% favorites wins only about 65% of the time. Anyone selling 'locks' is either uninformed or deliberately misleading; treat the word as a red flag and walk away.
Long Shot: An outcome priced at high odds with a low implied probability of winning. Long-shot markets (futures, exotic props, large underdog moneylines) tend to be overbet by recreational players seeking large payouts - the classic 'favorite-longshot bias' documented in horse-racing and sports-betting research, leading to structurally negative ROI on long shots on average.

M

Market Maker: A sportsbook that accepts large limits, originates lines, and operates on thin margins because their business model is informed price discovery rather than recreational volume. Pinnacle, Circa Sports, Bookmaker, and BetCRIS are the primary global market makers. Their closing lines are widely treated as the best available estimate of fair odds.
Maximum Bet: The highest stake a sportsbook will accept on a particular market at the current price. Maximums vary by market (high for NFL sides, low for obscure player props), by time (low at open, higher near close on sharp books), and by account (winning bettors at soft books are routinely max-limited to single-digit dollars).
Middle: Betting both sides of a market at different lines hoping the result lands between them, winning both. Example: betting Patriots -2.5 at one book and Bills +3.5 at another, then winning both if the game lands on 3. True middling opportunities are rare; the more common 'middle' play is buying around a key number for partial coverage of pushes.
Money Management: The discipline of sizing bets to survive variance and grow bankroll over time. Standard approaches include flat units (1%–2% per bet), confidence-weighted units (1–5 unit scale), and fractional Kelly (¼ to ½ of full Kelly). The single biggest preventable cause of betting bankruptcy is overstaking - even +EV bettors bust if they size too aggressively relative to their edge.
Moneyline: A straight bet on which team or competitor wins the event, with no spread applied. The simplest bet type and the format used internationally. Moneyline prices map directly to implied probability, making them the cleanest market for thinking about edges and no-vig conversions.

N

No-Vig Line: The market price stripped of the sportsbook's margin - an estimate of the fair odds the market would offer with zero hold. Calculated by dividing each side's implied probability by the sum of all implied probabilities. The no-vig line is the baseline a +EV bettor must beat, not the line they need to match.

O

Off the Board (OTB): A market the sportsbook has temporarily removed from offer, usually due to breaking injury news, weather uncertainty, or a referee assignment the book has not yet priced in. OTB status signals book uncertainty, not necessarily bettor opportunity - the market often reopens at a sharply different number.
Off-Market Line: A price meaningfully different from the consensus across other sportsbooks - sometimes a soft spot a bettor can exploit, sometimes news the rest of the market hasn't yet absorbed. Off-market lines lasting more than a few minutes at a major book usually signal either a slow update or a deliberate book position; both deserve scrutiny before betting.
Opening Line: The first price posted on a market when it goes live. Opening lines have lower limits than closing lines and are a target for sharp action looking to set fair value early. Beating the opener with consistent CLV is the strongest single signal that a bettor's process is sharper than the market.
Over / Under: A wager on whether the combined score will be more or less than a posted total. Totals are sensitive to pace, weather (NFL), umpires (MLB), and rule changes (NBA three-point era). Public bettors historically lean over, which has produced a persistent though shrinking edge on unders in primetime nationally televised games.
Overround: The amount by which the implied probabilities of all outcomes on a market sum above 100%. Mathematically equivalent to the book's theoretical hold. A two-way market at -110/-110 has an overround of 4.76%; a three-way market (1X2 soccer) typically has 5%–8%; a 30-runner horse race can exceed 20%.

P

Parlay: A single ticket combining multiple legs; all legs must win for the parlay to pay. Payouts are calculated by multiplying decimal odds, but because vig is stacked into each leg, true parlay EV is meaningfully worse than the multiplied price suggests. A 4-leg parlay of -110 favorites pays +1228 but should pay closer to +1300 at no-vig prices.
Pick'em: A market with no favorite - both sides are priced essentially even, typically -110 on each. Common in evenly-matched soccer and NFL games. A pick'em moneyline implies the book sees the game as roughly a coin flip after vig is stripped.
Pleaser: The inverse of a teaser - adjust spreads against your team in exchange for higher payouts. Pleasers carry vig markup that is almost always -EV in expectation regardless of the underlying handicap. Marketed as 'big payout' products, they function similarly to long-shot parlays in the math: high variance, structurally negative.
Point Spread: A handicap applied to the favorite (negative) and underdog (positive) to balance betting on both sides. The most heavily wagered market in US team sports. The spread is the market's best estimate of the most likely margin of victory, and prices around it (typically -110) reflect the small remaining uncertainty about which side will cover.
Power Rating: A numeric strength score assigned to each team, used to project spreads and totals before adjusting for situational factors (home field, rest, injuries, weather). Public power ratings include KenPom and Bart Torvik for college basketball, SP+ and FPI for college football, and DVOA/EPA-based ratings for the NFL. Custom power ratings are the foundation of most analytical bettor workflows.
Promo Abuse: Systematically taking advantage of sportsbook promotions, boosts, profit boosts, and free bets to extract +EV from offers regardless of underlying handicap. A boosted odds market priced above no-vig fair value is a literal positive expected value bet. Books increasingly restrict promo abusers via T&Cs limiting which accounts qualify for future offers.
Prop Bet: A wager on an individual event within a game - a player's points, the first scorer, total receptions, etc. Player props often carry 6%–10% hold and have lower limits than main markets, making them a frequent target for analytical bettors who can model individual usage and matchup-specific projections better than the book's automated pricing.
Public Money: Aggregate wagering from recreational bettors. Historically biased toward favorites, overs, popular teams, and primetime games. 'Fading the public' has produced small structural edges in specific spots over decades, but the effect has weakened as books increasingly target and limit sharp action while welcoming public volume.
Pulled Off the Board: A market temporarily removed from offering, usually due to breaking injury news, rule uncertainty, or weather. Status is typically resolved within minutes to hours and the market reopens at a meaningfully different price. Pulled markets are an indicator that the book is repricing rather than that the bettor has new opportunity.
Push: A tie result that returns the original stake. No win, no loss. Pushes are most common on spreads and totals that land exactly on the posted number - which is why NFL spreads of -3 push roughly 9% of the time, the highest push rate of any common number in any major sport.

R

Reduced Juice: A market priced at lower vig than standard - e.g. -105 instead of -110 on a spread, or a 5-cent line in baseball. Reduced juice markets are structurally easier to beat: at -105 the break-even win rate is 51.2% vs 52.4% at -110, a 1.2-point shift directly equivalent to adding 1.2% of edge to every bet.
Reverse Line Movement: When a line moves opposite to the majority of bets - e.g. 75% of tickets on the favorite at -3 but the line moves to -2.5. Strong evidence that a minority of bettors put down enough money (sharp action) to move the market. By the time RLM appears on public consensus dashboards, the original value is usually gone - it tells you which side professionals like, not that the price is still good.
ROI: Return on investment - profit divided by total amount wagered, expressed as a percentage. A bettor who risks $100,000 across a year and profits $3,000 has a 3% ROI. Sustained ROI of 1%–3% is professional-level; 5%+ over thousands of bets is exceptional. Win rate alone is misleading because it ignores stake variability and odds.
Round Robin: A wager that automatically generates every possible smaller parlay combination from a set of selected legs - e.g. a 4-team round robin by 2s creates six 2-team parlays. Round robins distribute variance differently than a single large parlay but still pay the parlay vig on every combination, so their effective hold is similar to standalone parlays.
Run Line: Baseball's spread, traditionally set at ±1.5 runs. Because MLB games are decided by 1 run roughly 28% of the time, the run line carries meaningful price swings: a -1.5 favorite is often priced as a small underdog on the moneyline. Alternate run lines (±2.5, ±0.5) offer additional flexibility at adjusted vig.

S

Same-Game Parlay (SGP): A parlay whose legs all come from a single game. Heavily repriced by books due to correlation between legs (a team's moneyline and over often move together). Effective hold on SGPs typically ranges from 15% to 25%, compared to ~5% on a standard straight bet - among the highest-margin products in modern sportsbook offering.
Sharp: A professional or highly disciplined bettor whose action moves markets. Sharps are identified by sustained positive CLV across thousands of bets, not by any single result. Sharp accounts are routinely limited or banned by retail US sportsbooks but welcomed at market-making books (Pinnacle, Circa) whose business model is to absorb sharp action and use it to set lines.
Sharp Book: A sportsbook that takes large limits from professionals and does not aggressively limit winning accounts - Pinnacle, Circa Sports, Bookmaker, BetCRIS. Sharp books operate on lower margins and rely on volume from informed action to set efficient lines, which is why their closing lines are widely treated as the best available estimate of fair price.
Soft Book: A sportsbook that takes mostly recreational action, copies lines from sharp books or vendor feeds, and quickly limits or bans winning bettors. Most US retail sportsbooks (DraftKings, FanDuel, BetMGM, etc.) operate as soft books - they compete on user experience and promos, not on line quality.
Stake: The amount of money risked on a single bet. Consistent staking discipline (using units, capping per-bet exposure as a percentage of bankroll) is the single most important defense against variance-driven bankruptcy, more important than win rate or pick quality in the short run.
Stale Line: A price that lags the rest of the market after news or movement elsewhere - a primary source of +EV for fast bettors. A stale line is rarely a permanent edge; it represents a soft book's seconds-to-minutes delay updating after a sharp move, and the bettor's edge is roughly the gap between the stale line and current no-vig fair value at sharp books.
Steam: Rapid, near-simultaneous line movement across many sportsbooks triggered by coordinated heavy action. Typically originates at sharp-taking books (Pinnacle, Circa, Bookmaker) and propagates to the rest of the market within minutes. Chasing steam is dangerous for retail bettors because the price they can actually take is post-move; steam is more useful as confirmation of an existing thesis.
Straight Bet: A single wager on one outcome - the simplest bet type and the foundation of most disciplined betting workflows. Straight bets carry the lowest hold (4%–5% on standard spreads/totals) compared to parlays (10%+ effective) and exotic props (often 8%+).

T

Tease: Verb form of teaser - to move spreads or totals in your favor across multiple legs at the cost of lower payout odds. The most-studied profitable teaser is the 6-point NFL teaser crossing through both 3 and 7 (the 'Wong teaser'), which has shown positive historical EV though book repricing has narrowed the edge.
Teaser: A parlay variant that lets you adjust spreads or totals in your favor at the cost of lower payout odds. Standard 6-point NFL teasers crossing through key numbers 3 and 7 (e.g. -7.5 to -1.5, or +1.5 to +7.5) - the 'Wong teaser' - have produced long-run +EV in historical samples, though books have repriced teasers more conservatively in recent years.
Three-Way Market: A market with three possible outcomes - typically win, lose, or draw in soccer and hockey regulation markets. Three-way pricing carries slightly higher overround than two-way moneylines because the book is pricing three implied probabilities into a sum that must exceed 100% by their margin.
Tissue Price: A horse racing term for the bookmaker's pre-market estimate of fair odds before public action shifts the price. Functionally equivalent to a no-vig power-rating projection in team sports - the tissue is the book's analytical baseline, not the final offered price.
Total: The combined score of both teams for a game - the basis of over/under bets. Totals respond more strongly to pace and game-script factors than spreads do, which is why pace-adjusted analytics, weather, and umpire/referee assignments are central to total-bet research.
Tout: Someone selling betting picks. The vast majority of touts are not profitable bettors over the long run; selling picks is often more lucrative than betting itself, with no skin in the game. Before paying for picks, demand audited records spanning at least 1,000+ bets across multiple sports and verifying positive CLV - most touts cannot produce either.
True Hold: The realized margin a sportsbook keeps after actual results, which can differ from theoretical hold due to bet distribution and outcome variance. Public hold reports from state regulators show true hold by sport - typically 7%–10% on NFL, 5%–7% on NBA, and double-digit hold on parlays - meaningfully above theoretical hold because of parlay and prop concentration.
True Odds: The actual probability of an outcome, expressed as odds, ignoring sportsbook margin. No one knows true odds exactly - the best public approximation is the no-vig closing line at a sharp book. A bettor's edge is the gap between their own probability estimate and the no-vig market price.

U

Underdog: The team or outcome expected to lose, indicated by a plus sign in American odds. Underdogs cover spreads at roughly 50% over the long run (after vig), which is the natural consequence of efficient markets. Apparent underdog edges in specific spots (NFL home dogs after a loss, MLB dogs at sharp books) are small, slow-moving, and increasingly priced in.
Unit: A standardized fraction of your bankroll - typically 1% - used to size bets consistently and communicate stake size across bettors with different bankrolls. A '3-unit play' from a 1% unit bettor risks 3% of bankroll. Standardizing on units enforces discipline and makes long-term ROI comparable across bettors and seasons.

V

Value: Any bet where the offered odds give a better return than the true probability would justify - i.e. a positive expected value bet. Value bettors focus on price discrepancies between books, soft lines posted before sharp action arrives, and props where their own model outperforms the book's. The goal is identifying mispricings, not predicting winners.
Variance: The natural swings in results around the expected value. Even a 56% bettor at -110 has roughly a 1-in-4 chance of being underwater after 200 bets, purely from variance. Variance is not a flaw in betting - it is the mechanism that makes edges available, because outcome noise prevents the market from converging to perfect efficiency.

Y

Yield: Profit divided by total stake, often expressed per 100 units staked. A more bet-size-aware metric than win rate because it accounts for how much was risked on each bet. Professional tipsters and tracked bettors are typically evaluated on yield over thousands of bets - sustained yields of 2%–5% are excellent; sustained yields above 8% over large samples are exceedingly rare and worth independent verification.