Terms

The language of betting. Terms that appear elsewhere in Learn link back here.

105 terms

Account Closure / BanBooks
A book removing a customer entirely, usually because they win.
ActionSlang
Having money on a game.
Alternate LinesBets
Spreads or totals different from the main line, offered at different prices.
American OddsOdds
The -110 / +150 format used by US books. A minus number is what you risk to win $100; a plus number is what you win on a $100 bet.
Arbitrage (Arb)Bets
Bets across books that guarantee a profit because their prices disagree. Books watch for it and limit arbers quickly.
Backdoor CoverSlang
A late, meaningless score that decides the spread.
Bad BeatSlang
Losing a bet that looked won late in the game.
BankrollSlang
Money set aside only for betting. In UNIT League, your unit balance.
BeardingBooks
Placing bets through someone else's account, usually after being limited. It breaks book rules and can be prosecuted as fraud, a felony in many states.
Bid / Ask / SpreadMarkets
The best price to buy, the best price to sell, and the gap between them.
Bonus Bet / Site CreditBooks
Promo money where only the winnings are paid out, not the stake. A $100 bonus bet at even odds is worth about $50.
Break-even RateOdds
The win percentage you need just to lose nothing. At -110 it's 52.38%, so being right half the time still loses money.
Buying PointsSlang
Paying extra juice to move a line in your favor.
Cash OutBets
Settling a bet early at a price the book sets, usually with extra margin built in.
CFTCMarkets
The Commodity Futures Trading Commission, the federal regulator that oversees event contracts.
ChalkSlang
The favorite, or betting favorites.
ChasingSlang
Betting more to recover losses. One of the clearest warning signs of problem gambling.
Closing Line Value (CLV)Books
Whether the price you got beat the closing price. It's the best available measure of betting skill, and exactly what books track to find winners.
Cooked / Got ThereSlang
Lost / won.
Decimal OddsOdds
The total return per $1 staked, including your stake. 2.50 returns $2.50 on a $1 bet ($1.50 profit).
DegenSlang
A compulsive or reckless bettor. Often worn as a badge of honor, which is worth noticing: it makes a real problem sound like a personality.
Event ContractMarkets
A yes/no contract that pays a fixed amount, such as $1, if the event happens and nothing if it doesn't.
Exchange vs. SportsbookMarkets
On an exchange you trade against other users, not the house. The exchange profits from fees instead of your losses.
Expected Value (EV)Odds
The average profit or loss per bet over the long run. +EV bets make money over time, -EV bets lose it. With the vig included, almost every bet is -EV.
FadeSlang
Betting against someone or something.
Fair / No-vig OddsOdds
The odds with the book's margin removed, reflecting the true probability the market implies.
Favorite / UnderdogOdds
The side expected to win / the side expected to lose. Favorites pay less; underdogs pay more.
Fractional OddsOdds
The 5/2 format, mostly used in the UK. 5/2 means you win $5 for every $2 staked.
FuturesBets
Bets on long-term outcomes like a champion or MVP. Your money is tied up for months, often at high hold.
Gambler's FallacyMath
Believing “I'm due.” Past results don't change the odds of the next bet.
Gambling WinningsTaxes
Taxable income, whether or not you receive a tax form.
GeofencingBooks
Location checks that confirm you're in a state where betting is legal.
GGR (Gross Gaming Revenue)Books
Handle minus winnings paid out. The book's take before expenses.
HandleBooks
The total amount wagered with a book.
HedgeBets
Betting against your own position to lock in a result or cut risk.
HoldOdds
The percentage of all money wagered that the book keeps. Straight bets hold around 4-5%; parlays and props often 20-30% or more.
HookBets
The half-point on a line (-3.5) that makes a tie against the spread impossible.
Implied ProbabilityOdds
The win chance the odds suggest: 1 ÷ decimal odds. 2.00 implies 50%; -110 (1.91) implies 52.4%.
Itemized DeductionTaxes
You must itemize, rather than take the standard deduction, to deduct any gambling losses.
Juice (UNIT League)League
In UNIT League, Juice is the enhancements you add to a runner (CLV, Team, and Edge cards) that change odds, stakes, or payouts. The opposite of the sportsbook meaning: it works for you.
Kalshi / PolymarketMarkets
The major current prediction market platforms. Named here as examples, not endorsements.
Kelly CriterionMath
A formula for sizing bets based on your edge and the odds: stake = (bp − q) ÷ b, where b is the net decimal odds, p your win chance, and q = 1 − p. Most pros bet a fraction of Kelly because it assumes you know your edge exactly. Its precise, odd-looking stakes are also a red flag to books.
KYCBooks
“Know Your Customer.” The identity verification required to bet and withdraw. It ties every account to one real person.
LimitingBooks
A book capping how much a winning bettor may wager, sometimes down to a few dollars.
Line / NumberBooks
The current price or spread on a bet.
Line MovementBooks
Price changes driven by betting action or news.
LiquidityMarkets
How much can be traded without moving the price.
Live / In-play BettingBets
Betting while the game is happening, with odds that update every play.
LockSlang
A “sure thing.” There isn't one.
Loss Deduction LimitTaxes
Losses are deductible only up to your winnings, and starting in 2026 only 90% of losses count. You can owe tax in a year you lost money overall.
Maker / Taker FeesMarkets
Fees for adding liquidity (maker) versus taking existing orders (taker). The exchange's version of the vig.
Market Maker (Prediction Markets)Markets
A firm that keeps posting buy and sell orders on both sides of a contract so others always have someone to trade with, earning the bid/ask spread. Big sportsbooks are entering prediction markets in this role, which puts the house back on the other side of many trades.
Market Maker (Sportsbooks)Books
A book that sets sharp prices and accepts large bets, such as Pinnacle or Circa.
Market TakerMarkets
A trader who fills an order already on the order book instead of posting a new one. Takers pay the spread and usually the higher fee. Most casual traders are takers.
Max Bet / Bet LimitBooks
The largest stake a book will accept on a bet.
MiddleBets
Two bets on the same game that can both win if the result lands between the two lines.
MoneylineBets
Pick the winner outright, with no point spread.
Near-miss EffectMath
Almost-wins, like a parlay that missed by one leg, that feel like progress and keep you betting.
Negative-sum GameMath
A game where total money out is less than total money in. With the book taking its cut, bettors as a group always lose.
Offshore BookBooks
An unlicensed site operating outside US regulation, with no guarantee you'll ever be paid.
Opening / Closing LineBooks
The first price posted, and the final price just before the event starts.
Order BookMarkets
The list of open buy and sell orders on a contract.
OverroundOdds
How far a market's implied probabilities add up past 100%. Two sides at -110 add to 104.8%; the extra 4.8% is the book's margin.
Palp / Obvious ErrorBooks
Short for palpable error. The rule books use to void bets they say were mispriced, which almost always means bets they lost.
ParlayBets
Multiple bets combined into one where every leg must win. The book's edge compounds on each leg.
Parlay Prayer / Lotto TicketSlang
A long-shot parlay with a tiny chance of hitting.
Pick'emOdds
A game with no clear favorite. The spread is zero, or both sides are priced about the same.
Playthrough / RolloverBooks
How much you must wager before bonus funds can be withdrawn, paying vig every time.
Point SpreadBets
A handicap that evens out a matchup. The favorite must win by more than the line; the underdog can lose by less than the line (or win) and still cover.
Prediction MarketMarkets
An exchange where users trade contracts on real-world outcomes.
Price as ProbabilityMarkets
A contract priced at $0.62 implies a 62% chance of the event happening.
Promo / Odds BoostBooks
An improved price used for marketing, often on bets that already carry high hold.
Prop BetBets
A bet on something other than the final result, such as player stats or the first scorer.
PushBets
A tie against the line. The stake is refunded.
Recency BiasMath
Overweighting the last few results.
Regulatory Gray AreaMarkets
As of 2026, whether sports event contracts fall under federal commodity rules or state gaming law is actively contested in courts and legislatures.
ResolutionMarkets
How and when a contract is settled, and by whose rules.
Responsible Gaming ToolsBooks
Deposit limits, time limits, and cool-off periods that books are required to offer.
Retail / Soft BookBooks
A mass-market book that copies lines from market makers and limits winners.
Reverse Line Movement (RLM)Slang
The line moving against the side most of the public is betting, a sign of sharp money on the other side.
ROIOdds
Return on investment: profit divided by total amount wagered. Even the best bettors rarely sustain more than a few percent.
Round RobinBets
Every possible smaller parlay from a set of picks. 4 picks in 2-leg combinations makes 6 parlays, and 6 times the parlay edge.
RunnerLeague
A player in a UNIT League syndicate. Each runner has their own unit balance and Juice.
Same-game Parlay (SGP)Bets
A parlay built from outcomes in a single game. Books price in the correlation between legs, and SGPs carry some of the highest hold in the industry.
Sample SizeMath
The number of bets needed before results mean anything. A hot month proves very little; it takes thousands of bets to separate skill from luck.
Self-exclusionBooks
Voluntarily banning yourself from betting, at one book or statewide.
SharpSlang
A skilled, winning bettor. Books limit sharps quickly.
Sportsbook / BookBooks
A company that takes bets. It sets the odds and is the other side of every wager.
Square / Public / RecreationalSlang
A casual bettor. Books welcome squares and send them promos.
State Tax TreatmentTaxes
Varies by state, and some states allow no deduction for losses at all.
SteamSlang
Sudden, sharp line movement across many books at once, usually from professional money.
Sunk CostMath
Continuing to bet because of what you've already lost.
SweatSlang
Nervously watching a live bet.
SyndicateLeague
In UNIT League, a league of runners competing with the same starting units. In real betting, a group of professionals pooling money and information.
TailSlang
Copying someone else's bet.
TeaserBets
A parlay where you move the lines in your favor in exchange for a lower payout.
TiltSlang
Emotional, impaired betting after losses.
Total (Over/Under)Bets
A bet on whether the combined score lands above or below a number set by the book.
Tout / CapperSlang
Someone selling picks. Ask the obvious question: if they could reliably win, why would they sell?
Trap LineSlang
A line believed to bait the public into the wrong side.
UnitSlang
A standard bet size, usually 1-2% of bankroll. In UNIT League, units are the fake currency you play with.
VarianceMath
The natural swings in results. Even a bettor with a real edge can lose for months.
Vig / JuiceOdds
Short for vigorish. The book's built-in fee on a bet, hidden inside the odds rather than charged separately.
W-2GTaxes
The IRS form issued for certain larger gambling wins.
WhaleSlang
A very high-stakes bettor.