Lewis & Short

alcyŏnēus and -nĭus (halc-), a, um, adj. [Alcyone], pertaining to Alcyone or alcyon (v. alcedo).

      1. a. Alcyonei dies = alcedonia (q. v.), Col. 11, 2.
      2. b. Alcyoneum medicamen, or absol.: alcyŏnēum, i, n., or even alcyŏnĭum. sea-foam, used as a remedy for spots on the face: alcyoneo utuntur ad oculorum cicatrices, Plin. 32, 8, 27, § 86; cf. Cels. 5, 6, 18, n. 26.