union

Etymology

From Middle English unyoun, from Old French union, from Late Latin ūniō, ūniōnem (“oneness, unity”), from Latin ūnus (“one”).

noun

1. (countable) The act of uniting or joining two or more things into one.
2. (countable) The state of being united or joined; a state of unity or harmony.
3. (countable) That which is united, or made one; something formed by a combination or coalition of parts or members; a confederation; a consolidated body; a league.
4. (countable) A trade union; a workers' union.
5. (countable) An association of students at a university for social and/or political purposes; also in some cases a debating body.
6. (countable) A joint or other connection uniting parts of machinery, such as pipes.
7. (countable, set theory) The set containing all of the elements of two or more sets.
8. (countable) The act or state of marriage.
9. (uncountable, archaic, euphemistic) Sexual intercourse.
10. (countable, programming) A data structure that can store any of various types of item, but only one at a time.
    Unions are useful in those cases where you need to keep track of a value that can be represented as different data types during the lifetime of the program. 2008, Kris Bell, Lars Ivar Igesund, Sean Kelly, Learn to Tango with D, page 58
11. (countable, now rare, archaic) A large, high-quality pearl.
12. (historical) An affiliation of several parishes for joint support and management of their poor; also the jointly-owned workhouse.

verb

1. (set theory) To combine sets using the union operation.

adj

1. Belonging to, represented by, or otherwise pertaining to a labour union.
   Actors have to be union to get work here.