(Ἐνιπεύς), a river-god in Thessaly, who was beloved by Tyro, the daughter of Salmoneus. Poseidon, who was in love with her, assumed the appearance of Enipeus, and thus visited her, and she became by him the mother of twins, Pelias and Neleus. (Apollod. 1.9.8.) Ovid (Ov. Met. 6.116) relates that Poseidon, having assumed the form of Enipeus, begot by Iphimedeia two sons, Otus and Ephialtes. Another river-god of the same name occurs in Elis, who is likewise connected with the legend about Tyro. (Strab. viii. p.356.)
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890