association

/əˌsoʊsiˈeɪʃ(ə)n/
/əˌsoʊʃiˈeɪʃ(ə)n/

noun

(often in names) a group of people organized for a joint purpose.

the National Association of Broadcasters

alliance,consortium,coalition,union,league,guild,syndicate,corporation,federation,confederation,confederacy,conglomerate,cooperative,partnership,amalgamation,merger