The Oxford Thesaurus An A-Z Dictionary of Synonyms - union n.

1) uniting, unity, combining, combination, joining, junction, conjoining, conjunction, allying, alliance, associating, association, coalition, amalgamating, amalgamation, fusing, fusion, marrying, marriage, confederating, confederation, confederacy, synthesizing, synthesis, mixing, mixture, federation, togetherness: Monarchies favour the union of Church and State. 2) alliance, association, organization, society, circle, fraternity, club, fellowship, team, ring, gang, syndicate, coalition, party, confederation, confederacy, federation, Bund, league, consortium, bloc, cartel, trust: The countries formed a union to control their joint economies. 3) joint, seam, splice, junction, conjunction, graft, weld; coupling: The union between the two pieces may be stronger than the material itself. 4) agreement, accord, harmony, harmoniousness, congruity, coherence, compatibility, unanimity, unity: The union of the various elements in the painting was skilfully effected.