validity vs validness

validity and validness both are nouns.

Word	Noun	Adjective	Verb	Adverb
validity	Yes	No	No	No
validness	Yes	No	No	No

As nouns, validity and validness are synonyms defined as:

validity and validness: the quality of having legal force or effectiveness

validity (noun)	validness (noun)
the quality of having legal force or effectiveness	the quality of having legal force or effectiveness
the quality of being valid and rigorous