Στύξ

Styx comes from the Greek verb stygein, meaning 'to hate' or 'to abhor.' The river of hatred. In Hesiod's Theogony, Styx was both a river and a goddess — a daughter of Oceanus who sided with Zeus during the war against the Titans. As a reward, Zeus made her waters the medium of the most binding oath in the cosmos. Any god who swore on the Styx and lied would fall into a deathlike coma for nine years, then spend nine more years exiled from Olympus. Eighteen years of punishment for a single lie.

Homer and later poets placed the Styx as one of five rivers in the underworld, along with Acheron (sorrow), Lethe (forgetfulness), Phlegethon (fire), and Cocytus (wailing). The dead crossed the Styx on Charon's ferry, paying one obol for passage — which is why the Greeks placed coins on the eyes or in the mouths of corpses. The river was geography and theology at once: it was a physical boundary and a moral one.

The adjective 'Stygian' entered English in the 16th century, meaning 'of or relating to the river Styx' and by extension 'dark, gloomy, infernal.' Milton used it in Paradise Lost (1667): 'the Stygian council.' The word carried the underworld's darkness into English poetry and stayed there. By the 19th century, 'Stygian gloom' was a fixed phrase in Gothic fiction. The river had become a synonym for impenetrable darkness.

In 1972, Dennis DeYoung formed a rock band in Chicago and named it Styx. The name was chosen partly because it sounded like 'sticks' (they played in people's backyards) and partly because the river of the dead felt appropriately dramatic for prog rock. The band sold over 54 million albums. Outside of music, Styx has entered computing (the Styx protocol for networked file systems) and astronomy (a small moon of Pluto, discovered in 2012). The river of hatred now orbits the god of the dead.