Styx, in Greek mythology, river of Hades that the souls of the dead had to cross on their journey from the realm of the living. It was a sacred river, and by its name even the gods took their most solemn oaths. The river was personified as a nymph, daughter of Oceanus and Tethys and mother of Nike. There is a river Styx in the N Peloponnesus (in ancient Arcadia).

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.

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