Sports Betting Glossary
The terms that actually matter for profitable betting, defined in plain language — no slang for its own sake, no tout-speak.
- Bankroll
- Money set aside exclusively for betting, whose total loss you could absorb. The denominator for all sensible bet sizing. Bankroll management guide →
- Beat rate (CLV beat rate)
- The percentage of your bets whose odds were better than the closing line. Above 50% over a large sample indicates you time the market well.
- Bookmaker margin (vig / juice / overround)
- The built-in house edge: implied probabilities in a market summing past 100%. A 1.91/1.91 two-way market carries about a 4.7% overround.
- Closing line
- The final odds available just before an event starts — the market’s most informed estimate of the true probability, having absorbed all news and sharp money.
- Closing line value (CLV)
- How much better (or worse) your odds were than the closing line: (bet odds − closing odds) ÷ closing odds × 100. The most reliable public indicator of betting skill. Full CLV guide →
- Decimal odds
- Odds expressed as total return per unit staked: 2.50 returns 2.5 units for 1 staked (1.5 profit). Implied probability = 1 ÷ decimal odds.
- Drawdown
- The decline from a bankroll peak to a subsequent trough, usually in percent or units. Managing maximum drawdown is the practical goal of bet sizing.
- Edge
- A positive difference between your true win probability and the probability implied by the odds. Edges are proven by CLV and long-run records, not by feelings.
- Expected value (EV)
- Average profit or loss per bet if repeated many times: EV = p × (odds − 1) − (1 − p). Positive-EV betting is the only long-term winning strategy. EV guide →
- Fractional Kelly
- Staking a fixed fraction (half, quarter) of the Kelly criterion recommendation to reduce variance and protect against estimation error.
- Handle
- Total amount wagered — by a bettor, on a game, or across a book. Your handle is the denominator of ROI.
- Hedging
- Betting the opposite side of an existing position to lock in profit or cap loss, accepting a worse combined price for certainty.
- Implied probability
- The win rate a price demands to break even: 1 ÷ decimal odds. Odds 2.00 = 50%, odds 1.50 = 66.7%.
- Kelly criterion
- Formula for growth-optimal bet sizing: f* = (b·p − q) ÷ b. Powerful with accurate probabilities, dangerous with optimistic ones. Kelly calculator →
- Limit (limited account)
- A bookmaker restricting how much a customer may stake — the standard response to accounts that consistently beat the closing line.
- Line movement
- Changes in odds between open and close, driven by money flow and news. Reading it well is a skill; chasing it after the fact is a leak. Line movement guide →
- Live betting (in-play)
- Betting during an event while odds change in real time. Higher bookmaker margins and faster decisions — statistically where tilted bettors lose the most.
- Longshot bias
- The market-wide tendency for long odds to be worse value than short odds, because casual money overpays for big payouts.
- Moneyline (1X2 / match odds)
- A bet on who wins, without a handicap. In three-way markets (soccer), the draw is a separate outcome.
- Parlay (accumulator)
- Multiple selections combined into one bet requiring all to win. Margins compound per leg, which is why books promote them so hard.
- ROI (return on investment)
- Net profit divided by total amount staked. The honest per-bet profitability measure — +3% to +5% sustained is professional-grade.
- Spread (handicap)
- A bet adjusted by a points margin. Comparing spread bets across different points is invalid — rigorous CLV only compares identical lines.
- Staking plan
- The predetermined rule for bet sizing — flat units, percentage, or fractional Kelly. Its job is to make sizing boring and survival certain.
- Steam
- A sudden, coordinated line move across many books at once, signaling respected money. Betting into it afterward buys a worse price.
- Tilt
- Emotionally driven betting after losses — raised stakes, faster bets, unfamiliar markets. The single most reliable destroyer of bankrolls. Tilt guide →
- Total (over/under)
- A bet on the combined score of both teams relative to a posted number, rather than on the winner.
- Unit
- A bettor’s standard stake, defined as a percentage of bankroll (commonly 1–2%). Records kept in units stay comparable as the bankroll changes.
- Value bet
- A bet whose odds exceed the fair odds for its true probability — i.e., positive EV. “Value” without a probability estimate is just an opinion.
- Void (push)
- A cancelled or tied bet with the stake returned. Voids must still be recorded — holes in a record corrupt every statistic computed from it.