Bolt
A sudden veering to the inside or outside rail, often caused by the horse spooking or shying from something.
Bleeder
A horse that bleeds due to a ruptured blood vessel during a race or workout. The medication Lasix can fix this problem.
Trifecta
A wager picking the first, second and third horses in the exact order. A trifecta box means paying more to ensure the horses can finish in any order in the top three spots.