Lewis & Short

† ŏnyx, ychis, m. and f., = ὄνυξ (a fingernail; hence, from its color).

  1. I. Fem., a kind of yellowish marble, onyx, of which vessels of many kinds were made; it was also used for mlaying floors, Plin. 36, 7, 12, § 59: totāque effusus in aulā Calcabatur onyx, Luc. 10, 116; calcatusque tuo sub pede lucet onyx, Mart. 12, 50, 4.
    1. B. Masc., a vessel of onyx, an onyx-box: nardi parvus onyx, Hor. C. 4, 12, 17; murrheus, an ointment-box, Prop. 3, 8 (4, 9), 22; cf.: Syrio munere plenus onyx, id. 2, 10 (3, 5), 14.
      In this signif. also as fem.: unguentum fuerat, quod onyx modo parva gerebat, Mart. 7, 94, 1.
  2. II. A yellowish precious stone, an onyx, Plin. 37, 6, 24, § 90
  3. III. The female of a mussel of the scallop species, Plin. 32, 9, 32, § 103.