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"
the shape or manner in which things come together and a connection is made
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"
- link up
make contact or come together
"The two roads join here"
come into the company of
"She joined him for a drink"
cause to become joined or linked
"join these two parts so that they fit together"
- bring together
become part of
become a member of a group or organization
"He joined the Communist Party as a young man"
- fall in - get together