familiarity vs indecorum

familiarity and indecorum both are nouns.

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

As nouns, familiarity and indecorum are synonyms defined as:

Other synonyms of familiarity include impropriety, liberty.

familiarity (noun)	indecorum (noun)
an act of undue intimacy	an act of undue intimacy
usualness by virtue of being familiar or well known	a lack of decorum
close or warm friendship
a casual manner
personal knowledge or information about someone or something