n. Any instrument of offense; anything used, or designed to be used, in attacking an enemy, as a sword, a dagger, a club, a rifle, or a cannon.n. n. Any object, particular, or instrumentality that may be of service in a contest or struggle, or in resisting adverse circumstances, whether for offense or defense; anything that may figuratively be classed among arms.n. In zoology, any part or organ of the body which is or may be used as a means of attack or defense, as horns, hoofs, claws, spurs, stings, spines, teeth, electric organs, etc.; an arm or armature.To arm with weapons.