Odds: The ratio or percentage chance of a player winning. For example, if a player makes a bet on a horse with 10:1 odds to win and the horse wins, the payout would be $10 for every $1 bet.

Off: A term used in gambling to refer to a losing bet.

Off-Track Betting: Commonly known as online bets or phone in bets made at a racetrack.

One-roll Bet: A term in craps used to describe a win or loss on one roll of the dice.

On-Tilt: A poker term used to describe a player who is on a losing streak resulting in poor and sometimes aggressive betting.

Open: A term used to describe the first bet made.

Outside Bets: A bet involving 12-18 numbers at a time on the outside of the betting layout in roulette.

Overlay: A bet made by a player that gives an edge over the casino.