hollowness vs insincerity

hollowness and insincerity both are nouns.

Word	Noun	Adjective	Verb	Adverb
hollowness	Yes	No	No	No
insincerity	Yes	No	No	No

As nouns, hollowness and insincerity are synonyms defined as:

hollowness and insincerity: the quality of not being open or truthful; deceitful or hypocritical

Other synonyms of hollowness include falseness.

hollowness (noun)	insincerity (noun)
the property of having a sunken area	the quality of not being open or truthful; deceitful or hypocritical
the quality of not being open or truthful; deceitful or hypocritical
the state of being hollow: having an empty space within