In Greek mythology, a river of the underworld. The name comes from a Greek word that denotes both hatred and extreme cold, and it expresses loathing of death. In the epics of Homer, the gods swore by the water of Styx as their most binding oath. Hesiod personified Styx as the daughter of Oceanus and the mother of Emulation, Victory, Power, and Might. The ancients believed that its water was poisonous and would dissolve any vessel except one made of the hoof of a horse or an ass.