UN

UK: /ˌjuːˈɛn/ US: (ən)

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UN abbreviation

1. United Nations

WordReference Random House Learner's Dictionary of American English © 2025

un-¹ ,prefix. 

1. un- is used very freely to form adjectives and the adverbs and nouns formed from these adjectives. It means "not,'' and it brings negative or opposite force:
   unfair, unfairly, unfairness;
   unseen;
   unfitting;
   unformed;
   unheard-of;
   unrest;
   unemployment.

un-² ,prefix. 

1. • un- is attached to verbs, and means "a reversal of some action or state, or a removal, a taking away, or a release'':
     unbend;
     uncork;
     unfasten.
   • un- is also attached to some verbs to intensify the meaning:
     unloose (= let loose with force).

UN or U.N., an abbreviation of:

1. Government, United Nations.

WordReference Random House Unabridged Dictionary of American English © 2025

un (ən), pron. [Dial.]

1. Slang Terms one:
   young uns; He's a bad un.

Also, 'un. 
UN ,

1. Government, See United Nations (def. 1).

Also, U.N. 
un-¹ ,

1. a prefix meaning "not,'' freely used as an English formative, giving negative or opposite force in adjectives and their derivative adverbs and nouns (unfair;
   unfairly;
   unfairness;
   unfelt;
   unseen;
   unfitting;
   unformed;
   unheard-of;
   un-get-at-able), and less freely used in certain other nouns (unrest;
   unemployment).

• Middle English un-, on-, Old English; cognate with Dutch on-, Gothic, German un-, Old Norse ū-, ō-; akin to Latin in-, Greek an-, a-. See a-⁶, an-¹, in-³

Synonyms

See in- ³.

un-² ,

1. a prefix freely used in English to form verbs expressing a reversal of some action or state, or removal, deprivation, release, etc. (unbend;
   uncork;
   unfasten;
   etc.), or to intensify the force of a verb already having such a meaning (unloose).

• Middle English, Old English un-, on-; cognate with Gothic and-, Dutch ont-, German ent-; akin to Latin ante, Greek antí; compare ante-, anti-

Note

See un- ¹.

Collins Concise English Dictionary © HarperCollins Publishers::

'un, un / ən/ pronoun

1. a spelling of one: that's a big 'un

This spelling is intended to reflect a dialectal or informal pronunciation

Collins Concise English Dictionary © HarperCollins Publishers::

un- prefix

1. (freely used with adjectives, participles, and their derivative adverbs and nouns: less frequently used with certain other nouns) not; contrary to; opposite of: uncertain, uncomplaining, unemotionally, untidiness, unbelief, unrest, untruth

Etymology: from Old English on-, un-; related to Gothic on-, German un-, Latin in-

un- prefix:forming_verbs

1. denoting reversal of an action or state: uncover, untangle
2. denoting removal from, release, or deprivation: unharness, unman, unthrone
3. (intensifier): unloose

Etymology: from Old English un-, on-; related to Gothic and-, German ent-, Latin ante