1. Bred from the best blood through a long line; pure-blooded; -- said esp. of horses.
2. Having the characteristics of fine breeding; aristocratic.

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.