I. A making level, levelling: “fortasse qui Archimedis libros legit, dicet non posse fieri veram ex aqua librationem,” Vitr. 8, 6, 3.—
II. A horizontal position, level: “circa terrae librationem,” Vitr. 6, 1, 5.—
III. A hurling off, hurling, slinging, Diom. p. 473 P.