darned vs infernal

darned is not a noun while infernal is a noun.

Word	Noun	Adjective	Verb	Adverb
darned	No	Yes	No	No
infernal	Yes	Yes	No	No

As adjectives, darned and infernal are synonyms defined as:

Other synonyms of darned include blame, blamed, blasted, blessed, damn, damned, deuced, goddam, goddamn, goddamned.

darned (noun)	infernal (noun)
	an inhabitant of Hell

darned (adjective)	infernal (adjective)
expletives used informally as intensifiers	being of the underworld
	characteristic of or resembling Hell
	of or pertaining to or characteristic of a very uncontrolled and intense fire
	expletives used informally as intensifiers
	extremely evil or cruel; expressive of cruelty or befitting hell