Lewis & Short

Hippocrēnē, ēs, f., = Ἱπποκρήνη,

  1. I. a fountain near Mount Helicon, sacred to the Muses, and which is fabled to have been produced by a stroke of Pegasus’s hoof, Ov. F. 5, 7; Sol. 7 med. (in Hor. Ep. 1, 3, 10: fons Pindaricus, and in Pers. prol. 1: fons caballinus).
  2. II. Derivv.
    1. A. Hippocrē-naeus, a, um, adj., of or belonging to Hippocrene: fontes, Auct. de Laud. Herc. 5.
    2. B. Hippocrēnĭdes, um, f., the Muses so named from the Hippocrene, Serv. Verg. E. 7, 21.