How to pronounce stygian

1 : of or relating to the river Styx. 2 : extremely dark, gloomy, or forbidding the stygian blackness of the cave.

1 of or relating to the river Styx. 2 Chiefly literary. a dark, gloomy, or hellish. b completely inviolable, as a vow sworn by the river Styx. (C16: from Latin Stygius, from Greek Stugios, from Stux Styx; related to stugein to hate)

Definition: extremely dark, gloomy, or forbidding. The “dark and gloomy” sense of stygian is a figurative one, as the original meaning of the word (which may also be found in capitalized form) was decidedly literal (“of or relating to the river Styx”).