Thoroughbred/ˈθɜːrəʊbred/ Definition 1 of 2Pro Tip 1/3Breed Specific Specifically refers to a breed of horses known for racing; don't use for other animals. The Kentucky Derby features some of the fastest thoroughbreds. Pro Tip 2/3Not All Horses Not all horses are thoroughbreds; this term is for ones with verified pedigree. You can tell that horse is a thoroughbred by its graceful movements. Pro Tip 3/3Cultural Prestige Thoroughbreds are often associated with prestige and high-class sporting events. Attending a thoroughbred race is seen as a high-society activity.