overlay
A horse going off at higher odds than it appears to warrant based on its past performances.
overnight race
A 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.
overweight
Surplus weight carried by a horse when the rider cannot make the required weight.
owner
The full owner or part owner of a registered Standardbred.
pace
A gait in which the legs of a horse move in lateral pairs.
pacesetter
The horse that is running in front (on the lead).