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
characterized by hopelessness; filled with gloom; "gloomy at the thought of what he had to face"; "gloomy predictions"; "a gloomy silence"; "took a grim view of the economy"; "the darkening mood"
lighted by or as if by twilight; "The dusky night rides down the sky/And ushers in the morn"-Henry Fielding; "the twilight glow of the sky"; "a boat on a twilit river"