damp vs dampen

damp is a noun but dampen is not a noun.

Word	Noun	Adjective	Verb	Adverb
damp	Yes	Yes	Yes	No
dampen	No	No	Yes	No

As verbs, damp and dampen are synonyms defined as:

Other synonyms of damp include break, soften, weaken.

As verbs, dampen is a hyponym of damp; that is, dampen is a word with a more specific, narrower meaning than damp:

Other hyponyms of damp include deafen, damp, deaden.

As verbs, damp and dampen are synonyms defined as:

Other synonyms of damp include deaden.

As verbs, dampen is a hypernym of damp; that is, dampen is a word with a broader meaning than damp:

Other hypernyms of damp include break, damp, soften, weaken.

As verbs, damp and dampen are synonyms defined as:

Other synonyms of damp include dull, muffle, mute, tone down.

damp (noun)	dampen (noun)
a slight wetness

damp (adjective)	dampen (adjective)
slightly wet

damp (verb)	dampen (verb)
lessen in force or effect	lessen in force or effect
make vague or obscure or make (an image) less visible	make moist
restrain or discourage	check; keep in check (a fire)
deaden (a sound or noise), especially by wrapping	make vague or obscure or make (an image) less visible
	reduce the amplitude (of oscillations or waves)
	suppress or constrain so as to lessen in intensity
	deaden (a sound or noise), especially by wrapping