goddamn vs goddam

goddamn and goddam both are adjectives.

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

As adjectives, goddamn and goddam are synonyms defined as:

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

As adverbs, goddamn and goddam are synonyms defined as:

goddamn and goddam: expressing anger, despair, frustration, approval, or surprise

Other synonyms of goddamn include goddamned.

goddamn (adjective)	goddam (adjective)
used as expletives	expletives used informally as intensifiers
expletives used informally as intensifiers

goddamn (adverb)	goddam (adverb)
expressing anger, despair, frustration, approval, or surprise	expressing anger, despair, frustration, approval, or surprise