Bolt

A sudden veering to the inside or outside rail, often caused by the horse spooking or shying from something.

Also Eligible

A horse that is entered but does not draw into the body of the field due to too many entries, and thus is not permitted to start unless there are enough scratches to shrink the field size.

Show Wager

Betting on a horse to finish in the first three spots, which pays out the same whether they win or run second or third.