invalidness vs invalidity

invalidness and invalidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
invalidness	Yes	No	No	No
invalidity	Yes	No	No	No

As nouns, invalidness and invalidity are synonyms defined as:

invalidness and invalidity: illogicality as a consequence of having a conclusion that does not follow from the premisses

invalidness (noun)	invalidity (noun)
illogicality as a consequence of having a conclusion that does not follow from the premisses	illogicality as a consequence of having a conclusion that does not follow from the premisses