infernal

Short definition from Wiktionary

Adjective

1. 1
   Of or relating to hell, or the world of the dead; hellish.
2. 2
   Of or relating to a fire or inferno.
3. 3
   Stygian, gloomy.
4. 4
   Diabolical or fiendish.
5. 5
   Very annoying; damned.

Noun

1. 1
   An inhabitant of the infernal regions, a demon.