Sports betting has a language of its own, and it is not always beginner friendly. Terms like devigging, closing line value, and middling get thrown around as if everyone already knows them, which leaves newer bettors guessing and experienced ones filling gaps they never quite closed.

This glossary fixes that. Below you will find clear definitions for the terms that actually come up, organized alphabetically, written in plain language. Bookmark it and come back whenever something does not make sense.

A

Action
Any bet with money at stake. Also used to describe overall betting volume on a game, as in a matchup that is getting heavy action.

Alternate Line
A point spread, total, or player prop offered at a different number than the standard line, with the odds adjusted accordingly. Because fewer people bet them, alternate lines are often priced less carefully than main lines.

American Odds
The odds format used most commonly in the United States, shown as a positive or negative number. Negative odds indicate the favorite and show how much you must stake to win 100. Positive odds indicate the underdog and show how much you would win on a 100 stake. Our implied probability calculator converts between formats instantly.

Arbitrage
Betting every possible outcome of an event across different sportsbooks so that you profit regardless of the result. It works when the combined implied probability of all outcomes falls below 100 percent. Our full breakdown of arbitrage betting covers the math in detail, and the arbitrage calculator works out your stake split.

ATS
Against the spread. A team's record when the point spread is applied rather than the straight up result.

B

Bad Beat
A loss that was effectively won until a late and often meaningless event flipped the result. Common in totals and player props.

Bankroll
The pool of money set aside specifically for betting, kept separate from everyday finances. How you manage it matters more than most bettors realize, which is why bankroll management is a skill in its own right.

Bonus Bet
A promotional wager offered by a sportsbook where the stake is not returned on a win. Its real cash value is always less than face value, which our bonus bet conversion calculator works out.

Book
Short for sportsbook, the operator accepting your bets.

Buying Points
Paying worse odds in exchange for moving a spread or total in your favor. Usually a poor value proposition at standard pricing.

C

Chalk
The favorite. Betting chalk means backing the side expected to win.

Closing Line
The final odds available immediately before an event begins. It is considered the market's most accurate estimate of true probability, because it reflects all available information and all sharp money.

Closing Line Value (CLV)
Whether the price you bet was better than the closing line. Consistently positive CLV is the strongest available indicator that your process is genuinely profitable, independent of short term results. Our guide to closing line value explains how to measure it.

Correlation
When the outcomes of two bets are linked, so one hitting makes the other more or less likely. Correlated legs concentrate risk more than most bettors expect.

Cover
Winning against the point spread rather than simply winning the game.

D

Decimal Odds
The odds format common outside the United States, expressed as the total return per unit staked including your stake. Odds of 2.50 return 2.50 total for every 1 wagered.

Devigging
Removing the sportsbook's margin from a set of odds to reveal the implied true probability. It is the foundational calculation behind identifying value, since you cannot know whether a price is good until you know what the fair price is. Use the no vig fair odds calculator to do it in seconds.

DFS
Daily fantasy sports. In a betting context this usually refers to pick'em apps like PrizePicks and Underdog, where you select more or less on player stat lines. Our guide to profiting on PrizePicks and Underdog covers the strategy.

Dog
Short for underdog, the side expected to lose.

E

Edge
The advantage you hold on a bet, measured as the gap between the true probability of an outcome and the probability implied by the odds.

Even Money
Odds where a winning bet returns a profit equal to the stake. Expressed as plus 100 in American odds or 2.00 in decimal.

Exchange
A platform where bettors trade against each other rather than against a sportsbook. Because there is no house margin, exchanges are structurally more beatable, as covered in our piece on exchanges and prediction markets.

Expected Value (EV)
The average result of a bet if it could be placed repeatedly. Positive expected value means the bet is profitable over time, negative means it loses. Our explainer on +EV betting covers the concept fully, and the expected value calculator runs the numbers for you.

F

Fade
To bet against something, whether a team, a public opinion, or another bettor's pick.

Favorite
The side expected to win, indicated by negative American odds.

Flex Play
A DFS slip type that still pays out, at reduced odds, if one leg misses. Lower variance than an all or nothing play, with correspondingly lower upside.

Futures
A bet on an outcome decided later in a season, such as a championship winner or a season win total.

G

Grinder
A bettor who profits through high volume and small consistent edges rather than large individual wins.

Grand Salami
A single bet on the combined total of every game on a given slate, most common in hockey and baseball.

H

Handicapper
Someone who analyzes games to predict outcomes, often selling picks.

Hedging
Placing a bet on the opposite side of a position you already hold, to lock in profit or limit a loss.

Hit Rate
The percentage of your bets that win. Useful, but on its own it says nothing about profitability, because what matters is whether that rate clears the break even threshold for the prices you are taking.

Hold
The percentage a sportsbook expects to keep from all money wagered on a market. Effectively the book's margin. The hold calculator measures it on any market.

I

Implied Probability
The probability an outcome must have for a set of odds to be break even. Calculated by dividing 1 by the decimal odds. Comparing implied probability to true probability is how value is identified, and our implied probability calculator handles the conversion.

In Play
See Live Betting.

J

Juice
See Vig.

K

Kelly Criterion
A formula that determines the optimal fraction of your bankroll to wager based on the size of your edge. Most professionals use a fractional version to reduce volatility. Covered in depth in our bankroll management guide, with a Kelly calculator to size each bet.

L

Limit
The maximum a sportsbook will accept on a given bet. Books frequently reduce limits for bettors who win consistently.

Line
The odds or point spread offered on a market.

Line Movement
Changes to a line between its opening and close, driven by betting volume, injury news, and other information.

Line Shopping
Comparing the same bet across multiple sportsbooks to take the best available price. One of the simplest and most reliable ways to improve long term results.

Live Betting
Wagering on a game already in progress. Lines move rapidly and are often priced less accurately than pregame markets.

Longshot
A heavy underdog at long odds.

M

Middle
A position where two bets on opposite sides of a game can both win if the final result lands between the two numbers. The act of creating one is called middling.

Moneyline
A bet on which side simply wins, with no point spread involved.

N

No Vig Odds
Odds with the sportsbook margin stripped out, representing the market's estimate of true probability. The benchmark against which value is measured. Calculate them with our no vig fair odds calculator.

O

Odds
The price of a bet, expressing both the potential payout and the implied probability of the outcome.

Off the Board
A market a sportsbook has removed from betting, usually because of injury uncertainty or unusual action.

Over
A bet that a total will finish above the posted number.

P

Parlay
A single bet combining multiple selections, all of which must win. Payouts are larger, but so is the risk, and the book's margin compounds with each added leg. Work out combined pricing with the parlay odds calculator.

Pick'em
A market with no favorite, or a DFS format where you choose more or less on player stat lines.

Player Prop
A bet on an individual player's statistical performance rather than the game result. Because books price thousands of them, props tend to be softer than main markets. See our guide to betting NFL player props and the prop optimizer tutorial.

Poisson Distribution
A statistical model used to project the likelihood of scoring outcomes in low scoring sports such as soccer and hockey. Our Poisson calculator applies it to match projections.

Point Spread
A margin of victory applied to level the field between two sides.

Prediction Market
A platform where contracts pay out based on real world outcomes, with prices representing implied probability. Kalshi and Polymarket are prominent examples.

Public Money
Wagers from recreational bettors. Often concentrated on favorites and popular teams, which can push lines away from true probability.

Push
A tie against the spread or total, where stakes are returned.

R

Recreational Bettor
A casual bettor who wagers for entertainment rather than profit. Their collective action is what creates many of the mispricings sharp bettors target.

ROI
Return on investment. Total profit divided by total amount staked, expressed as a percentage. A more meaningful measure of skill than raw profit.

S

Sharp
A professional or highly skilled bettor. Also used to describe a well priced line or a sportsbook known for accurate pricing.

Sharp Money
Wagers from informed bettors. Because it tends to correct mispriced lines, tracking where sharp money lands is a useful signal, which is why our sharp money view exists alongside standard value screening. The sharp money tool tutorial walks through how to read it.

Steam
A rapid, significant line move driven by heavy coordinated action.

Sure Bet
See Arbitrage.

T

Teaser
A parlay where you adjust the spread in your favor on each leg in exchange for a reduced payout.

Total
The combined score of both teams, bet as over or under. Also called the over under.

True Probability
The actual likelihood of an outcome, as distinct from the probability implied by the odds. The gap between the two is where value lives.

U

Under
A bet that a total will finish below the posted number.

Underdog
The side expected to lose, indicated by positive American odds.

Unit
A standardized bet size, typically 1 percent of bankroll, used to measure results independently of bankroll size. Our breakdown of how many units you can realistically make puts the measure in context.

V

Value
A bet where the true probability of winning exceeds the probability implied by the odds. Finding value consistently is the entire basis of profitable betting.

Variance
The natural swing in results caused by chance. Even a genuine edge produces losing stretches, which is why results must be judged over large samples.

Vig
Short for vigorish, the margin built into odds that guarantees the sportsbook a profit regardless of outcome. Also called juice. It is the reason a standard point spread bet requires roughly 52.4 percent accuracy just to break even. Measure it on any market with our vig calculator.

W

Wager
A bet.

Wiseguy
An older term for a sharp bettor.

Y

Yield
Another term for ROI, common outside the United States.

Putting the Terms to Work

Understanding the vocabulary is the first step. Applying it is where results come from, and nearly every term above connects back to the same underlying idea: find prices that are better than an outcome's true probability, and place enough of those bets for the math to surface.

That is what our +EV plays tool and player prop optimizer are built to do, by devigging sharp market pricing and surfacing the bets where genuine value exists.

If you would rather run the numbers yourself first, we offer free calculators for vig, expected value, implied probability, no vig fair odds, arbitrage, Kelly staking, hold, parlay odds, bonus bet conversion, and Poisson projections.

Please play responsibly. Sports betting carries real financial risk, and no strategy or tool guarantees a profit. If gambling is affecting your life, free and confidential support is available through the National Council on Problem Gambling. Must be of legal age in your jurisdiction.

Sports Betting Glossary: 75+ Terms Explained