zodiac constellation represented by a pair of scales, late Old English, from Latin libra "a balance, pair of scales," also "pound (unit of weight)," from Proto-Italic *leithra- "pound." De Vaan compares Greek litra "name of a Sicilian coin," which "was probably borrowed from an Italic language at the stage containing [-thr-]."
Not a separate constellation in ancient Greece, where it was khelae, "the claws" of adjacent Skorpios. Nativized in Old Norse as skala-merki. Meaning "person born under the sign of Libra" is from 1894. Related: Libral; Libran.