Bronco is a cowhand’s term for a bad-tempered or untamed horse. The word means rough or wild in Spanish. Cowhands also use the word bronco instead of mustang for the small, wild horses that roam the Western United States. Easterners sometimes call any untrained horse shipped from the West a bronco. The wild horses of the West are descended from horses brought by early Spanish explorers. Today, broncos are used to herd cattle and for roughriding competitions in rodeos. Broncos in rodeos are called broncs. See also Rodeo .