damned vs goddam

damned is a noun but goddam is not a noun.

Word	Noun	Adjective	Verb	Adverb
damned	Yes	Yes	No	Yes
goddam	No	Yes	No	Yes

As adjectives, damned and goddam are synonyms defined as:

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

damned (noun)	goddam (noun)
people who are condemned to eternal punishment

damned (adjective)	goddam (adjective)
expletives used informally as intensifiers	expletives used informally as intensifiers
in danger of the eternal punishment of Hell

damned (adverb)	goddam (adverb)
in a damnable manner	expressing anger, despair, frustration, approval, or surprise