Out of the MoneyA horse that finishes worse than third.
OverlayA horse going off at higher odds than it appears to warrant based on its past performances.
OvernightA sheet published by the racing secretary's office listing the entries for an upcoming racing card.
Overnight RaceA race in which entries close a specific number of hours before running (such as 48 hours), as opposed to a stakes race for which nominations close weeks and sometimes months in advance.
OverweightSurplus weight carried by a horse when the rider cannot make the required weight.