acheronian | sense examples, Usage and Definition from wordnet dictionary online

Adjective acheronian has 1 sense

Acheronian, Acherontic, Stygian - dark and dismal as of the rivers Acheron and Styx in Hades; "in the depths of an Acheronian forest"; "upon those roseate lips a Stygian hue"-Wordsworth
Antonym: light (indirect, via dark)