n. One who breaks young or wild horses to the saddle; in the army, a non-commissioned cavalry or artillery officer detailed to assist the riding-master, one being allowed to each troop or battery.n. Loosely, a horseman occupied with hard, rough work.n. One who breaks young or wild horses to the saddle; in the British army, a non-commissioned cavalry or artillery officer detailed to assist the riding-master, one being allowed to each troop or battery.n. A horseman accustomed to rough or hard riding, such as cow-boys or frontiersmen: applied specifically, in the late Spanish-American war, to the members of a volunteer regiment of cavalry, recruited partly from Western cow-boys.