union

(countable) The act of uniting or joining two or more things into one.

(countable) The state of being united or joined; a state of unity or harmony.

(countable) Something united, or made one; something formed by a combination or coalition of parts or members; a confederation; a consolidated body; a league.

In the autumn there was a row at some cement works about the unskilled labour men. A union had just been started for them and all but a few joined. One of these blacklegs was laid for by a picket and knocked out of time.

1918, W[illiam] B[abington] Maxwell, chapter XXII, in The Mirror and the Lamp, Indianapolis, Ind.: The Bobbs-Merrill Company, →OCLC:

(countable) A trade union; a workers' union.

(countable) An association of students at a university for social and/or political purposes; also in some cases a debating body.

(countable) A joint or other connection uniting parts of machinery, such as pipes.

(countable, set theory) The set containing all of the elements of two or more sets.

(countable) The act or state of marriage.

Sexual intercourse
sexual intercourse#English

(uncountable, archaic, euphemistic) Sexual intercourse.

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:

(countable, programming) A data structure that can store any of various types of item, but only one at a time.

Nonius the senator hath a purple coat as stiff with jewels as his mind is full of vices; rings on his fingers worth 20,000 sesterces, and[…]an union in his ear worth an hundred pounds' weight of gold […]

1624, Democritus Junior [pseudonym; Robert Burton], The Anatomy of Melancholy: […], 2nd edition, Oxford, Oxfordshire: […] John Lichfield and James Short, for Henry Cripps, →OCLC, partition II, section 3, member 3:

And in the cup an union shall he throw, Richer than that which four successive kings In Denmark's crown have worn.

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act V, scene ii]:

(countable, now rare, archaic) A large, high-quality pearl.

(historical) An affiliation of several parishes for joint support and management of their poor; also the jointly-owned workhouse.

en-noun

union (countable and uncountable, plural unions)

→ Bengali: ইউনিয়ন (iuniẏon) (learned)

unie

the act of uniting or the state of being united

sameining

the act or process of uniting; more rarely, the state of being united

միություն

that which is united; something formed by a combination of parts or members

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


union

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

en-verb

union (third-person singular simple present unions, present participle unioning, simple past and past participle unioned)

unions (present singular third-person)
unioning (participle present)
unioned (participle past)
unioned (past)


union

Actors have to be union to get work here.

Belonging to, represented by, or otherwise pertaining to a labour union.

The union government of India

en-adj

union (comparative more union, superlative most union)

more union (comparative)
most union (superlative)