Lewis & Short

lībra, ae, f. [cf. λίτρα; root cli-, clino], the Roman pound, of twelve ounces: as erat libra pondus, Varr. L. L. 5, § 169 Müll.: coronam auream libram pondo ex publica pecunia in Capitolio Iovi donum posuit, Liv. 4, 20: mulli binas libras ponderis raro exsuperant, Plin. 9, 17, 30, § 64: expende Hannibalem, quot libras in duce summo invenies? Juv. 10, 147: neque argenti in convivio plus pondo quam libras centum inlaturos, Gell. 2, 24, 2: dipondii pondo duas erant libras, Gai. Inst. 1, 122.

  • II. Transf.
    1. A. A measure for liquids: frumenti denos modios et totidem olei libras, Suet. Caes. 38.
  • B.
    1. 1. A balance, pair of scales: cum in alteram librae lancem animi bona imponebat, in alteram corporis, etc., Cic. Tusc. 5, 17, 51; cf. id. Fin. 5, 30, 91.
      1. 2. A water-poise, plummet-level, level, line: sin autem locus … pari libra cum aequore maris est, Col. 8, 17, 4: libratur autem dioptris aut libris aquariis aut chorobate, Vitr. 8, 6, 1.
        Hence, ad libram: alteram navem pluribus aggressus navibus in quibus ad libram fecerat turres, of equal height or of equal weight, Caes. B. C. 3, 40, 1.
      2. 3. Counterpoise, balance: contra flatus quoque pervicax libra Bononiensibus calamis, Plin. 16, 36, 65, § 161: aes et libra, v. aes.
      3. 4. The constellation Libra, The Balance, Verg. G. 1, 208; Ov. F. 4, 386; Plin. 18, 25, 59, § 221: felix aequato genitus sub pondere Librae, Manil. 4, 545.
      4. 5. Trop., a balance (poet.), Pers. 4, 10: animi cunctantis libra, Claud. Laud. Stil. 1, 75.