frivolity vs frivolousness

frivolity and frivolousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
frivolity	Yes	No	No	No
frivolousness	Yes	No	No	No

As nouns, frivolity and frivolousness are synonyms defined as:

frivolity and frivolousness: the trait of being frivolous; not serious or sensible

frivolity (noun)	frivolousness (noun)
acting like a clown or buffoon	the trait of being frivolous; not serious or sensible
something of little value or significance
the trait of being frivolous; not serious or sensible