stygian

adj

1. (alt-of, alternative)Alternative form of Stygian (“of or relating to the river Styx”).
2. (figuratively, literary)Infernal or hellish.
3. (figuratively, literary)Dark and gloomy.

   “The things which the Stygian darkness hid from my objective eye […]”

4. Having a luminosity below 0%.
5. (Greek)Of, by or relating to the river Styx in Greek mythology.
6. Of, by or relating to the Plutonian moon named after Styx.
7. (alt-of, alternative)Alternative form of stygian: dark and gloomy, or infernal and hellish.

   “Within all was black as the tomb. […] Feeling before him upon the floor with the butt of his spear, Tarzan entered the Stygian gloom.”

   “Or maybe Trump has designs on hell, viewing it as a totally unexploited real-estate opportunity to create some kind of Stygian Riviera.”

noun

1. An inhabitant of Styx (a moon of Pluto).

   “Stygians – natives of Styx”