familiarity vs impropriety

familiarity and impropriety both are nouns.

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

As nouns, familiarity and impropriety are synonyms defined as:

Other synonyms of familiarity include indecorum, liberty.

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