tumescence vs tumidness

tumescence and tumidness both are nouns.

Word	Noun	Adjective	Verb	Adverb
tumescence	Yes	No	No	No
tumidness	Yes	No	No	No

As nouns, tumidness is a hypernym of tumescence; that is, tumidness is a word with a broader meaning than tumescence:

tumescence: tumidity resulting from the presence of blood or other fluid in the tissues
tumidness: slight swelling of an organ or part

Other hypernyms of tumescence include tumidity.

tumescence (noun)	tumidness (noun)
tumidity resulting from the presence of blood or other fluid in the tissues	slight swelling of an organ or part