Of or relating to hell: infernal punishments; infernal powers.
Fiendish; diabolical: infernal instruments of war.
Abominable; awful: the infernal racket of the jackhammers.
[Middle English, from Old French, from Late Latin īnfernālis, from īnfernus, hell, from Latin, lower, underground; see dher- in Indo-European roots.] in·fer'nal·ly adv.