involvement vs affair

involvement and affair both are nouns.

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

As nouns, involvement and affair are synonyms defined as:

involvement and affair: a usually secretive or illicit sexual relationship

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

involvement (noun)	affair (noun)
the act of sharing in the activities of a group	a vaguely specified concern
a sense of concern with and curiosity about someone or something	a formal or official social gathering or ceremony of people
a connection of inclusion or containment	a usually secretive or illicit sexual relationship
a usually secretive or illicit sexual relationship
the condition of sharing in common with others (as fellows or partners etc.)