affair vs get together

affair and get together both are nouns.

Word	Noun	Adjective	Verb	Adverb
affair	Yes	No	No	No
get together	Yes	No	Yes	No

As nouns, get together is a hyponym of affair; that is, get together is a word with a more specific, narrower meaning than affair:

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

affair (verb)	get together (verb)
	get together socially or for a specific purpose
	become part of; become a member of a group or organization
	get people together