[n] a set containing all and only the members of two or more given sets; "let C be the union of the sets A and B"
[n] the shape or manner in which things come together and a connection is made
[v] make contact or come together; "The two roads join here"
[v] cause to become joined or linked
[v] become part of; become a member of a group or organization; "He joined the Communist Party as a young man"
[v] come into the company of; "She joined him for a drink"
[v] be or become joined or united or linked; "The two streets connect to become a highway"; "Our paths joined"; "The travelers linked up again at the airport"
articulation, bring together, conjoin, connect, fall in, get together, joint, junction, juncture, link, link up, sum, union, unite