(Κῖος), a son of Olympus, from whom Cios (Prusa) on the Propontis derived its name, as he was believed to have led thither a band of colonists from Miletus. (Schol. ad Theocrit. 13.30; ad Apollon. Rhod. 1.1177.) Strabo (xii. p.564) calls him a companion of Heracles who founded Cios on his return from Colchis.
[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