What does UNION mean?

noun

1. an organization of employees formed to bargain with the employer“you have to join the union in order to get a job”
2. the act of pairing a male and female for reproductive purposes“the casual couplings of adolescents”
3. the state of being joined or united or linked“there is strength in union”
4. the state of being a married couple voluntarily joined for life (or until divorce)“a long and happy marriage”
5. healing process involving the growing together of the edges of a wound or the growing together of broken bones
6. a political unit formed from previously independent people or organizations“the Soviet Union”
7. 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”
8. the occurrence of a uniting of separate parts“lightning produced an unusual union of the metals”