I. An instrument for boring, a borer, an auger, gimlet, Cato, R. R. 41, 3; Col. 4, 29, 15 sq.; Plin. 7, 56, 57, § 198; 17, 15, 25, § 116; 37, 13, 76, § 200.—
II. As a surgical instrument, a trephine, Cels. 8, 3.—
III. A military engine for boring through walls in sieges, Vitr. 10, 13, 7.