[Sp. bronco rough, rude; as applied to a horse, adopted on the Mexican frontier of U.S.] An untamed or half-tamed horse, or a cross between the horse and mustang; a native horse of California or New Mexico.
1883. E. Ingersoll, in Harper’s Mag., Feb., 428/1. There came rushing over the ridge-top … a ragged, tough broncho horse.
1884. Pall Mall Gaz., 22 Aug., 10/1. [He] was captured … stripped of every bit of clothing, and bound on the back of a wild bronco, which was started off by vigorous lashing.
