union

¹ American  

[yoon-yuhn] / ˈyun yən /

noun

1. the act of uniting two or more things.

   Antonyms:

   division, separation

2. the state of being united.

   Antonyms:

   division, separation

3. something formed by uniting two or more things; combination.

4. a number of persons, states, etc., joined or associated together for some common purpose.

   student union; credit union.

5. a group of states or nations united into one political body, as that of the American colonies at the time of the Revolution, that of England and Scotland in 1707, or that of Great Britain and Ireland in 1801.

6. the Union. the United States.

   The Union defeated the Confederacy in 1865.

7. a device emblematic of union, used in a flag or ensign, sometimes occupying the upper corner next to the staff or occupying the entire field.

8. the act of uniting or an instance of being united in marriage or sexual intercourse.

   an ideal union; an illicit union.

   Synonyms:

   liaison, wedlock

9. an organization of workers; a labor union.

10. Mathematics.

    1. Also called join, logical sum, sum.  the set consisting of elements each of which is in at least one of two or more given sets. ∪

    2. the least upper bound of two elements in a lattice.

11. the process or result of merging or integration of disjoined, severed, or fractured elements, as the healing of a wound or broken bone, the growing together of the parts in a plant graft, the fusion of pieces in a welding process, or the like.

12. the junction or location at which the merging process has taken place.

13. any of various contrivances for connecting parts of machinery or the like.

14. Textiles.

    1. a fabric of two kinds of yarn.

    2. a yarn of two or more fibers.

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Union ² American  

[yoon-yuhn] / ˈyun yən /

noun

1. a township in NE New Jersey.

2. a city in NW South Carolina.

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Union ¹ British  

/ ˈjuːnjən /

noun

1. 1. the union of England and Wales from 1543

   2. the union of the English and Scottish crowns (1603–1707)

   3. the union of England and Scotland from 1707

   4. the political union of Great Britain and Ireland (1801–1920)

   5. the union of Great Britain and Northern Ireland from 1920

2. 1. the United States of America

   2. the northern states of the US during the Civil War

   3. ( as modifier )

      Union supporters

3. short for the Union of South Africa

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union ² British  

/ ˈjuːnjən /

noun

1. the condition of being united, the act of uniting, or a conjunction formed by such an act

2. an association, alliance, or confederation of individuals or groups for a common purpose, esp political

3. agreement or harmony

4. short for trade union

5. the act or state of marriage or sexual intercourse

6. a device on a flag representing union, such as another flag depicted in the top left corner

7. a device for coupling or linking parts, such as pipes

8. (often capital)

   1. an association of students at a university or college formed to look after the students' interests, provide facilities for recreation, etc

   2. the building or buildings housing the facilities of such an organization

9. Also called: join.  maths a set containing all members of two given sets. Symbol: ⋃, as in A⋃B

10. 1. a number of parishes united for the administration of poor relief

    2. a workhouse supported by such a combination

11. textiles a piece of cloth or fabric consisting of two different kinds of yarn

12. (modifier) of or related to a union, esp a trade union

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union Scientific  

/ yo̅o̅n′yən /

1. A set whose members belong to at least one of a group of two or more given sets. The union of the sets {1,2,3} and {3,4,5} is the set {1,2,3,4,5}, and the union of the sets {6,7} and {11,12,13} is the set {6,7,11,12,13}. The symbol for union is .

2. Compare intersection

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Union Cultural  

1. The United States; especially the northern states during the Civil War, which remained with the original United States government. (Compare Confederacy.)

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Usage

What is a union? A union is a group of workers for a particular organization or industry who come together for collective bargaining with their employers. Labor unions and trade unions often work closely with employers to maintain the rights, wages, benefits, and liberties of the unionized workers, peacefully protesting when necessary. Broadly, a union is a combination of people or things. Any time two or more things come together physically, emotionally, or politically, they are said to be in a union. It could be as simple as the union of peanut butter and jelly on a sandwich. Two more important unions are a marriage and a civil union, which is a lesser alternative for a marriage. While a civil union doesn’t offer all of the rights and protections in the law that a marriage does, it is recognized by most governments as a permanent relationship with some rights and protections. A union might also refer to a larger group of people joined together for a common purpose besides labor issues, such as a credit union (an alternative to a traditional bank) and a student union, a place set aside on some college and university campuses for student activities. Example: The union of the companies went smoothly and everyone is benefitting.

Related Words

Union, unity agree in referring to a oneness, either created by putting together, or by being undivided. A union is a state of being united, a combination, as the result of joining two or more things into one: to promote the union between two families; the Union of England and Scotland. Unity is the state or inherent quality of being one, single, individual, and indivisible (often as a consequence of union): to find unity in diversity; to give unity to a work of art. See alliance.

Other Word Forms

• interunion noun
• misunion noun
• preunion adjective
• prounion adjective
• self-union noun

Etymology

Origin of union

First recorded in 1400–50; late Middle English, from Middle French, from Late Latin ūniōn-, stem of ūniō, from Latin ūn(us) “one” + -iō -ion

Explanation

A union is things coming together, or uniting, to make one. When the thirteen colonies that became the United States came together, they formed a union. Marriage is another kind of union. Workers come together to form trade unions so that together they can have a stronger voice negotiating with their employer. The word famously occurs in the Preamble (the introduction) to the United States Constitution: "We the people of the United States, in Order to form a more perfect Union...do ordain and establish this Constitution...." You may recognize the Latin root unum in union, as in e pluribus unum "from many, one," the motto on the seal of the United States.

Example Sentences

The union said talks had failed and accused TfL of refusing to make concessions.

From BBC • Apr. 20, 2026

Instead, the Mets’ struggles will no doubt become a talking point in the upcoming labor negotiations as evidence from the players’ union that money alone isn’t enough to guarantee success.

From The Wall Street Journal • Apr. 20, 2026

Nichols, who leads the Associated Administrators of Los Angeles/Teamsters Local 2010, started with a joke about her mere year and 10 months as a union leader.

From Los Angeles Times • Apr. 18, 2026

Mejia, a union organizer, ran on a platform of affordability for the working class, including increasing funding for child care and raising taxes on the highest earners.

From Salon • Apr. 18, 2026

The union raised enough money to free Fannie after she had served three months.

From "Fannie Never Flinched" by Mary Cronk Farrell

Related Words

• association
• club
• federation
• guild
• labor union
• league
• local
• society
• trade union