falsehood vs falsity

falsehood and falsity both are nouns.

Word	Noun	Adjective	Verb	Adverb
falsehood	Yes	No	No	No
falsity	Yes	No	No	No

As nouns, falsehood and falsity are synonyms defined as:

Other synonyms of falsehood include untruth.

falsehood (noun)	falsity (noun)
the act of rendering something false as by fraudulent changes (of documents or measures etc.) or counterfeiting	a false statement
a false statement	the state of being false or untrue