I. A leveller, esp. by means of a water-level, a surveyor, Cato, R. R. 22, 1; Front. Aquaed. 105: “superest ut tu libratorem vel architectum mittas, qui diligenter exploret, sitne lacus altior mari,” Plin. Ep. 10, 50, 3.—
II. One who throws or hurls weapons by hand (cf. funditor, a slinger): “funditores libratoresque excutere tela et proturbare hostem jubet,” Tac. A. 2, 20: “libratoribus funditoribusque attributus locus,” id. ib. 13, 39; Inscr. ap. Kellerm. Vigil. p. 55, n. 127.