The noun union has 11 senses (first 3 from tagged texts)
1. (27) union, labor union, trade union, trades union, brotherhood -- (an organization of employees formed to bargain with the employer; "you have to join the union in order to get a job")
2. (2) Union, North -- (the United States (especially the northern states during the American Civil War); "he has visited every state in the Union"; "Lee hoped to detach Maryland from the Union"; "the North's superior resources turned the scale")
3. (1) coupling, mating, pairing, conjugation, union, sexual union -- (the act of pairing a male and female for reproductive purposes; "the casual couplings of adolescents"; "the mating of some species occurs only in the spring")
4. union, unification -- (the state of being joined or united or linked; "there is strength in union")
5. marriage, matrimony, union, spousal relationship, wedlock -- (the state of being a married couple voluntarily joined for life (or until divorce); "a long and happy marriage"; "God bless this union")
6. union, conglutination -- (healing process involving the growing together of the edges of a wound or the growing together of broken bones)
7. union -- (a political unit formed from previously independent people or organizations; "the Soviet Union")
8. union, sum, join -- (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")
9. union -- (the occurrence of a uniting of separate parts; "lightning produced an unusual union of the metals")
10. union -- (a device on a national flag emblematic of the union of two or more sovereignties (typically in the upper inner corner))
11. union, unification, uniting, conjugation, jointure -- (the act of making or becoming a single unit; "the union of opposing factions"; "he looked forward to the unification of his family for the holidays")
Overview of adj union
The adj union has 2 senses (first 1 from tagged texts)
1. (4) Union, Federal -- (being of or having to do with the northern United States and those loyal to the Union during the American Civil War; "Union soldiers"; "Federal forces"; "a Federal infantryman")
2. union -- (of trade unions; "the union movement"; "union negotiations"; "a union-shop clause in the contract")