tumidity vs tumescence

tumidity and tumescence both are nouns.

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

As nouns, tumescence is a hyponym of tumidity; that is, tumescence is a word with a more specific, narrower meaning than tumidity:

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

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