Scratch

A horse is a scratch when injury or other necessity causes it to be withdrawn from the race.

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.

Condition Book

A list of upcoming races issued by the racing secretary, where the conditions of races to be run over the next few weeks are written.