Bet/Wager: The act of risking money on the outcome of an event.
Stake: The amount of money you place on a bet.
Odds: The measure of how likely an outcome is, and the payout it will provide.
- Fractional Odds (e.g., 5/1): Common in the UK. You win $5 for every $1 bet.
- Decimal Odds (e.g., 6.00): Common in Europe. Includes stake in the total return.
- Moneyline Odds (e.g., -150, +250): Common in the US. Shows how much you must bet to win $100 (-) or how much you win from a $100 bet (+).

Single Bet: A bet on one outcome.
Parlay/Accumulator: A bet with multiple outcomes. All must win for the bet to pay.
Each-Way Bet: A bet that covers both the win and place in a race.
Point Spread: A bet where one team is favored by a certain number of points.
Over/Under (Total): A bet on whether the total combined score will be over or under a set number.
Moneyline: A bet on who will win outright.
Futures: A bet placed well in advance (e.g., Championship winners).
Prop Bet: A bet on a specific outcome within a game (e.g., first goal scorer).

Hedging: Placing bets on both sides of an event to reduce risk.
Arbitrage: Betting on all outcomes with different bookies for a guaranteed profit.
Line Movement: Changes in odds or point spreads caused by betting activity.
Unit: A standardized bet size used for bankroll management.

Live/In-Play Betting: Placing bets while an event is ongoing.
Push: When the bet result lands precisely on the line, and the stake is refunded.
Bad Beat: A bet that loses in an especially unlucky way.
Value Bet: A bet where the odds are higher than the actual chance of an outcome.
Pari-Mutuel Betting: Pool betting (common in horse racing), where the total bet pool is divided among winners.

Reverse Line Movement (RLM)
When the betting line moves in the opposite direction of the majority of public bets. Often signals sharp or professional action.
Steam Move
A rapid and significant odds shift across multiple sportsbooks at once — typically caused by large wagers from sharp bettors.
True Odds / Implied Probability
The actual chance of an event happening, as opposed to the odds offered by the bookmaker (which include the vig).
No-Vig Odds
Odds stripped of the bookmaker’s margin (used to calculate true market probabilities).

Kelly Criterion
A bankroll management formula that calculates the optimal bet size to maximize growth while minimizing risk.
Expected Value (EV)
The average return of a bet if placed repeatedly —
- Positive EV (+EV) Bet: Expected to profit in the long run.
- Negative EV (-EV) Bet: Expected to lose in the long run.
Middling (Middle Bets)
Betting both sides of a line at different points to try to win both bets (e.g., bet Team A -3 and Team B +4 hoping the result lands on 3 or 4).
Correlated Parlay
A parlay where the legs are statistically connected (e.g., betting both a team to cover the spread and the over if they’re a high-scoring team).
Chasing Losses
Increasing stakes to recover prior losses — often considered dangerous.

Syndicate
A group of professional bettors pooling resources and data to place large bets strategically.
Wiseguy / Pro Bettor
A highly skilled bettor, often part of a syndicate or betting at scale.
Public Money
The money wagered by the general betting public (often more emotional, less analytical).
Sharp Money
Wagers from professional or highly skilled bettors.

Key Number
A critical margin in point spread betting where games often land (e.g., 3 or 7 in football).
Off the Board (OTB)
When a sportsbook temporarily removes a game from betting due to uncertain conditions (e.g., injury news).
Buy Points
Paying an extra price to adjust a point spread or total to a more favorable number.

Payout Percentage / Hold
The percentage of money retained by a bookmaker after paying out winnings — a measure of their edge.
Closing Line
The final odds or point spread offered before a game starts — used as a benchmark of market efficiency.
Derivative Market
Betting markets tied to specific segments of a game (e.g., 1st quarter spread, team total points).
Market Maker
A sportsbook or sharp bettor that sets or significantly influences the opening line.