Pari-Mutuel
A pool style wagering system, where all money input through betting is divided among those with winning tickets (save for various deductions by the track operators).
Bug
An apprentice jockey.
Rabbit
Also known as a pacemaker; this is a horse with no expected chance of winning but is used to prompt a quick pace on the front end of the race to the benefit of a stablemate who is a closer.

