1911 Encyclopædia Britannica/Holster

HOLSTER, a leather case to hold a pistol, used by a horseman and properly fastened to the saddle-bow, but sometimes worn in the belt. The same word appears in Dutch, from which the English word probably directly derives. The root is hel- or hul- to cover, and is seen in the O. Eng. heolster, a place of shelter or concealment, and in “hull” a sheath or covering. The German word for the same object, holfter, is, according to the New English Dictionary, from a different root.