Source : Webster's Revised Unabridged Dictionary (1913)

Thoroughbred \Thor"ough*bred`\, a.
   Bred from the best blood through a long line; pure-blooded;
   -- said of stock, as horses. Hence, having the
   characteristics of such breeding; mettlesome; courageous; of
   elegant form, or the like. -- n. A thoroughbred animal,
   especially a horse.

Source : WordNet®

thoroughbred
     adj : having a list of ancestors as proof of being a purebred
           animal [syn: {pedigree(a)}, {pedigreed}, {pureblood}, {pureblooded}]
     n 1: a well-bred person [ant: {mixed-blood}]
     2: a racehorse belonging to a breed that originated from a
        cross between Arabian stallions and English mares
     3: a pedigreed animal of unmixed lineage; used especially of
        horses [syn: {purebred}, {pureblood}]