intimacy vs affair

intimacy and affair both are nouns.

Word	Noun	Adjective	Verb	Adverb
intimacy	Yes	No	No	No
affair	Yes	No	No	No

As nouns, intimacy and affair are synonyms defined as:

Other synonyms of intimacy include affaire, amour, involvement, liaison.

intimacy (noun)	affair (noun)
close or warm friendship	a vaguely specified concern
a feeling of being intimate and belonging together	a formal or official social gathering or ceremony of people
a usually secretive or illicit sexual relationship	a usually secretive or illicit sexual relationship