Lewis & Short

Īris, is or idis (acc. Irim, Verg. A. 4, 694: Irin, Ov. and App.), f., = Ἶρις,

  1. I. the goddess of the rainbow, daughter of Thaumas and Electra, the sister of the Harpies, and the swift-footed messenger of the gods: Irim de caelo misit Saturnia Juno, Verg. A. 5, 606; 4, 700; 9, 803; Ov. M. 1, 271; 11, 631; 14, 830 al.
    Voc. Irī, Ov. M. 11, 585.
  2. II. Transf.
    1. A. The rainbow: Irin vulgo arcus esse aiunt, quando imago solis vel imago lunae umidam et cavam nubem densamque ad instar speculi colorat, etc., App. de Mundo, 16, p. 64, 10; cf. Sen. Q. N. 1, 3, 1 sqq.: iris erat in circuitu sedis, Vulg. Apoc. 4, 3; Amm. 20, 11, 26.
    2. B. A sweet-smelling plant, perh. the sword-lily, Plin. 21, 7, 19, § 40; Col. 12, 27; 12, 53, 2; Pall. 1, 37, 2.
    3. C. (Iris stone.) A precious stone, prob. a very pure six-sided prismatic crystal, Plin. 37, 9, 52, § 136.
    4. D. A river that flows into the Euxine Sea, Plin. 6, 3, 3, § 8; Val. Fl. 4, 600.