1. A pedigreed animal of unmixed lineage; used especially of horses; SYN. purebred, pureblood.
2. A well-bred person.
Horse bred for racing purposes. All racehorses are thoroughbreds, and all male thoroughbreds are direct descendants of one of three stallions imported into Britain during the 17th and 18th centuries: the Darley Arabian, Byerley Turk, and Godolphin Barb.