Lewis & Short

tĕrē̆bra, ae, f. (neutr. collat. form tĕ-rē̆brum, Hier. in Isa. 12, 44, 12 al.) [tero].

  1. 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.
  2. II. As a surgical instrument, a trephine, Cels. 8, 3.
  3. III. A military engine for boring through walls in sieges, Vitr. 10, 13, 7.

tĕrĕbrum, i, v. terebra init.