affaire vs affair

affaire and affair both are nouns.

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

As nouns, affaire and affair are synonyms defined as:

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

affaire (noun)	affair (noun)
a usually secretive or illicit sexual relationship	a vaguely specified concern
	a formal or official social gathering or ceremony of people
	a usually secretive or illicit sexual relationship