Sports Betting Glossary

The vocabulary of +EV betting, defined in plain English — from expected value and the vig to devigging, closing line value, and the Kelly criterion. No jargon left unexplained.

A

American Odds

The US odds format, shown with a plus or minus sign. Negative odds (e.g. −150) tell you how much you must stake to win $100; positive odds (e.g. +150) tell you how much you win on a $100 stake. See also Decimal Odds and Fractional Odds.

Arbitrage Arb

Betting every outcome of a market across different sportsbooks whose combined prices guarantee a profit no matter what happens. Real but rare: the margins are thin, the windows are short, and books limit accounts that do it often. Related to the Middle.

B

Bankroll

The pool of money set aside specifically for betting, kept separate from money you need to live on. Every sound staking plan — including Kelly — is expressed as a fraction of your bankroll.Read: The Kelly Criterion →

Beard

A person who places bets on behalf of someone else — typically to disguise a sharp bettor whose own action would be limited or refused by the book.

C

Closing Line Value CLV

Whether the price you got beat the line at the moment it closed. If you consistently bet numbers better than the closing price, you're almost certainly a long-term winner — CLV is the single best predictor there is.Read: Closing Line Value →

D

Decimal Odds

The odds format common outside the US. It shows the total return per unit staked, including your stake: decimal 2.50 returns 2.5 units for every 1 unit bet (a 1.5-unit profit). See also American Odds.

Devigging

Removing the bookmaker's margin from a line so the outcomes' probabilities sum to a clean 100%, revealing their true likelihood. It's the essential step between a raw price and a fair price.Read: No-Vig & Fair Odds →

Devigged Probability

The fair probability of an outcome once the vig has been divided out. It's the number you compare against a book's price to decide whether a bet is +EV.

E

Edge

Your advantage on a bet: the gap between the price a book is offering and the fair price. A positive edge is exactly what makes a bet +EV. Quantify it with the EV calculator.

Expected Value +EV / −EV

The average outcome of a bet if you could repeat it many times. A +EV bet makes money on average and a −EV bet loses on average — even though any single bet can still win or lose. Long-term profit comes from placing +EV bets over and over.Read: What Is +EV Betting? →

F

Fractional Odds

The traditional UK format written as a fraction, e.g. 5/2. It shows profit relative to stake: 5/2 pays 5 units of profit for every 2 units staked. See also American and Decimal Odds.

H

Handle

The total amount of money wagered on an event, market, or book over a period. It's a volume figure the industry reports — not profit. The book's profit from that handle is its hold.

Hedge

Betting the opposite side of a position you already hold to lock in a profit or limit a loss, usually by accepting a smaller but more certain result. Distinct from arbitrage, which is set up as a pair from the start.

Hold

The percentage of total handle a sportsbook expects to keep as profit. It's driven by the vig built into the book's lines — higher vig, higher hold.

I

Implied Probability

The probability an outcome would need for its odds to be break-even. It's read straight off the odds, so it still contains the vig until you devig the line. Across a full market, implied probabilities sum to more than 100% — the overround.

J

Juice-Free

An informal way of saying no-vig or fair — a price or probability with the bookmaker's margin stripped out. (See also Juice, the margin itself.)

K

Kelly Criterion

A formula that sets your bet size as a fraction of bankroll based on your edge and the odds, maximizing long-term bankroll growth. Because full Kelly is volatile, most bettors stake a fraction of it (e.g. half or quarter Kelly).Kelly Calculator → · Read: The Kelly Criterion →

L

Limit

The maximum stake a book will accept on a bet. Sharp books like Pinnacle post high limits and welcome winners; soft books lower limits on, or ban, bettors who beat them.

Line Shopping

Comparing the same bet across multiple sportsbooks and always taking the best available price. It's the most basic requirement of +EV betting — a fractionally better number, repeated, is a real edge.

M

Middle

Betting both sides of a market at different numbers so a result landing between them wins both bets. If the result misses the middle, the two bets largely cancel, so the cost of trying is small. Related to arbitrage.

Moneyline

A bet on who wins the game outright, with no point spread involved. Priced in American odds.

N

No-Vig / Fair Odds

The price of a bet after the bookmaker's margin has been removed, reflecting an outcome's true probability. It's the benchmark you hold every book's price up against to spot value.Read: No-Vig & Fair Odds →

O

Odds Boost

A promotion where a book offers better-than-normal odds on a selection. On a market that's already fair or +EV, a boost can turn into a genuinely profitable bet; on a bad market it just makes a −EV bet slightly less bad.

Overround

The amount by which the implied probabilities of all outcomes in a market exceed 100%. That excess is the vig expressed as a percentage — the book's built-in edge.

P

Parlay

One bet combining several selections that must all win. Payouts multiply, but so does the compounded vig on every leg — which is why the vast majority of parlays are sharply −EV.

Pinnacle

A sportsbook known for low margins, very high limits, and not banning winners. Because sharp money is free to correct its prices, Pinnacle's lines are exceptionally accurate — the standard source bettors devig for fair odds.

Prop Bet

A wager on something specific within an event — a player's points, passing yards, or strikeouts — rather than the final result. Props are often softer and a common hunting ground for +EV bettors.

Push

A tie between your bet and the line — for example, a −3 favorite winning by exactly 3. Your stake is refunded and neither side wins or loses.

R

ROI

Return on investment: net profit divided by the total amount you staked, shown as a percentage. It reflects skill better than raw win rate, since it accounts for the odds you took.

S

Sharp / Square

A sharp is a skilled, disciplined bettor whose action can move lines; a square is a casual, recreational bettor. Markets watch sharp money because it's usually right — which is why sharp books' lines are so useful.

Spread

A handicap that levels a matchup: the favorite must win by more than the number to cover, while the underdog covers by losing by less than it — or winning outright. Also called the point spread or line.

Steam Move

A sudden, sharp line move that sweeps across many books at once, usually because respected money hit a number simultaneously. Chasing steam after it's moved is often too late to capture value.

T

Total (Over/Under)

A bet on whether the combined score of both teams finishes over or under a number the book posts.

U

Unit

A standardized bet size — commonly 1% of your bankroll — used to describe stakes and results consistently no matter how big anyone's bankroll is. "Up 10 units" means the same thing to everyone.

V

Vig / Juice Vigorish

The bookmaker's built-in commission — the reason a 50/50 market is priced −110 on both sides instead of +100. It's how books profit regardless of who wins, and removing it is the whole point of devigging.Read: No-Vig & Fair Odds →

Iron Marker is an analytics tool, not a sportsbook, and this glossary is educational — not betting or financial advice. Must be 21+. Problem gambling? Call 1-800-GAMBLER.