[stiks] 
| a river in the underworld, over which the souls of the dead were ferried by Charon, and by which the gods swore their most solemn oaths. |
| Styx (stĭks) n. Greek Mythology The river across which the souls of the dead are ferried, one of the five rivers in Hades. [Latin, from Greek Stux.] |
In classical mythology, one of the rivers of Hades, across which Charon ferried the souls of the dead. The gods occasionally swore by the river Styx. When they did so, their oath was unbreakable.
