1.Definition: being of the underworld
2.Definition: characteristic of or resembling Hell
"Infernal noise", "Infernal punishment"
3.Definition: expletives used informally as intensifiers
"An infernal nuisance"
4.Definition: extremely evil or cruel; expressive of cruelty or befitting hell
"Infernal instruments of war"
5.Definition: of or pertaining to or characteristic of a very uncontrolled and intense fire