swelling vs tumidness

swelling and tumidness both are nouns.

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

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

swelling (noun)	tumidness (noun)
the increase in volume of certain substances when they are heated (often accompanied by release of water)	slight swelling of an organ or part
something that bulges out or is protuberant or projects from its surroundings
an abnormal protuberance or localized enlargement