Nouns

(n)infernalan inhabitant of Hell“his roar made the infernals quake”

Adjectives

(a)infernalcharacteristic of or resembling Hell“infernal noise”, “infernal punishment”
(s)demonic, diabolic, diabolical, fiendish, hellish, infernal, satanic, unholyextremely evil or cruel; expressive of cruelty or befitting hell“something demonic in him — something that could be cruel”, “fires lit up a diabolic scene”, “diabolical sorcerers under the influence of devils”, “a fiendish despot”, “hellish torture”, “infernal instruments of war”, “satanic cruelty”, “unholy grimaces”
(s)blasted, blame, blamed, blessed, damn, damned, darned, deuced, goddam, goddamn, goddamned, infernalexpletives used informally as intensifiers“he's a blasted idiot”, “it's a blamed shame”, “a blame cold winter”, “not a blessed dime”, “I'll be damned (or blessed or darned or goddamned) if I'll do any such thing”, “he's a damn (or goddam or goddamned) fool”, “a deuced idiot”, “an infernal nuisance”
(a)infernalof or pertaining to or characteristic of a very uncontrolled and intense fire“infernal heat”
(a)infernalbeing of the underworld“infernal regions”