WordNet sense 1 (the shape or manner in which things come together and a connection is made):

articulation, joint, junction, juncture

WordNet sense 2 (a set containing all and only the members of two or more given sets):

sum, union

WordNet sense 3 (be or become joined or united or linked):

connect, link, unite

WordNet sense 4 (become part of; become a member of a group or organization):

fall in

WordNet sense 5 (cause to become joined or linked):

bring together

WordNet sense 6 (make contact or come together):

conjoin