tumidness vs tumescence

tumidness and tumescence both are nouns.

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

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

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

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