vapidity vs vapidness

vapidity and vapidness both are nouns.

Word	Noun	Adjective	Verb	Adverb
vapidity	Yes	No	No	No
vapidness	Yes	No	No	No

As nouns, vapidity and vapidness are synonyms defined as:

Other synonyms of vapidity include jejuneness, jejunity, tameness.

vapidity (noun)	vapidness (noun)
the quality of being vapid and unsophisticated	the quality of being vapid and unsophisticated