impropriety vs familiarity

impropriety and familiarity both are nouns.

Word	Noun	Adjective	Verb	Adverb
impropriety	Yes	No	No	No
familiarity	Yes	No	No	No

As nouns, impropriety and familiarity are synonyms defined as:

Other synonyms of impropriety include indecorum, liberty.

impropriety (noun)	familiarity (noun)
an act of undue intimacy	an act of undue intimacy
an indecent or improper act	usualness by virtue of being familiar or well known
an improper demeanor	close or warm friendship
the condition of being improper	a casual manner
	personal knowledge or information about someone or something