(Ἴθακος), a son of Pterelaus, a hero from whom Ithaca was believed to have derived its name. (Hom. Od. 17.207; Eustath. ad Hom. pp. 307, 1815; Hesych. s. v.) Odysseus, king of Ithaca, is sometimes simply called Ithacus, or the Ithacan. (Ov. Ep. ex Pont. 1.3, 33; Verg. A. 2.104.)
[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