From Longman Dictionary of Contemporary Englishracehorserace‧horse /ˈreɪshɔːs $ -hɔːrs/ noun [countable] DSHa horse specially bred and trained for racing
Examples from the Corpus
racehorse• Members will also have the chance to own a racehorse.• Champion racehorses run no faster today than they did half a century ago.• Donkeys have no objection to donkey work, but they can not stand being taken for racehorses or tractors.• Farnton, a high piece of ground in the parish, is a training track for racehorses.• Your average loony racehorse can do better.• At that hour, cars zip down Union Avenue, headed to the stables sheltering 1,800 pampered racehorses.• The owner of a sterile racehorse named Cigar said he would apply for permission to replicate the beast.• To her career as an actress, the always practical Lillie now added another: that of a highly successful racehorse owner. 