affiliation, association, tie, tie-up (noun)
a social or business relationship
"a valuable financial affiliation"; "he was sorry he had to sever his ties with other members of the team"; "many close associations with England"
the act of becoming formally connected or joined
"welcomed the affiliation of the research center with the university"
The relationship resulting from affiliating one thing with another.
A club, society or umbrella organisation so formed, especially a trade union.
In law, affiliation is the term to describe a partnership between two or more parties.