I. Orig. a plough-coulter, ploughshare, Plin. 18, 18, 48, § 171 sq.—
II. In gen., a knife; so a vintner's knife, Col. 4, 25, 2; 12, 45, 4; a butcher's knife, Plaut. Rud. 1, 2, 46; Liv. 3, 48, 5: “qui ad cultrum bovem emunt,” i. e. for slaughter, Varr. R. R. 2, 5, 11; Suet. Tib. 25; Scrib. Comp. 13; a razor: “cultros metuens tonsorios,” Cic. Off. 2, 7, 25: “cultrum tonsorium super jugulum meum posui,” Petr. 108, 11; Plin. 7, 59, 59, § 211; a hunting-knife, Petr. 40; Suet. Aug. 19; id. Claud. 13; a cook's knife, Plaut. Aul. 3, 2, 3; Varr. ap. Non. p. 195, 16: “tympanum versatile, in cultro collocatum,” placed on the edge, on the small side, perpendicularly, Vitr. 10, 14; “in the same sense: in cultrum collocare,” id. 10, 10.—Prov.: sub cultro, under the knife, i. e. in extreme peril or distress, Hor. S. 1, 9, 74.