frivolous vs sincerity

frivolous is not a noun while sincerity is a noun.

Word	Noun	Adjective	Verb	Adverb
frivolous	No	Yes	No	No
sincerity	Yes	No	No	No

frivolous (noun)	sincerity (noun)
	the quality of being open and truthful; not deceitful or hypocritical
	the trait of being serious
	a quality of naturalness and simplicity
	an earnest and sincere feeling

frivolous (adjective)	sincerity (adjective)
not serious in content or attitude or behavior