Over/Under

Over-under or over/under (O/U) bets are wagers in which a sports book will predict a number for a statistic in a given game (usually the combined score of the two teams), and bettors wager that the actual number in the game will be either higher or lower than that number. For example, in Super Bowl XXXIX, most Las Vegas casinos set the over-under for the score of the game at 46.0.

A bettor could wager that the combined score of the two teams would be either more than or less than that number. Since the combined score of that game was 45, anyone who had bet on "under" won.