tumescence vs tumidity

tumescence and tumidity both are nouns.

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

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

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

Other hypernyms of tumescence include tumidness.

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