Un-

//ʌn// prefix

prefix ·Uncommon ·Advanced level

Definitions

Prefix
  1. 1
    not morpheme

    "un- + educated → uneducated (“not educated”)"

  2. 2
    the inverse of a specified action morpheme

    "un- + dress → undress (“to take one's clothes off”)"

  3. 3
    Used for the digit one to form systematic element names of elements whose existence has been predicted, and which have not yet been given a trivial name. morpheme

    "un- (“1”) + bi- (“2”) + un- (“1”) + -ium (element suffix) → unbiunium (“element 121”)"

  4. 4
    lack of morpheme

    "un- + conformity → unconformity (“lack of conformity”)"

  5. 5
    deprive of, release from, free from, remove from, extract from morpheme

    "un- + cage → uncage (“to release from a cage”)"

Show 3 more definitions
  1. 6
    Used to form large numbers as the first in the sequence. morpheme

    "un- + decillion (“10³³”) → undecillion (“10³⁶”)"

  2. 7
    contrary to traditional norms; unconventional morpheme

    "un- + conference → unconference"

  3. 8
    intensifying a verb that already suggests opposition or removal morpheme, rare

    "un- + loosen → unloosen"

Example

More examples

"un- + educated → uneducated (“not educated”)"

Etymology

Etymology 1

From Middle English un-, from Old English un-, from Proto-West Germanic *un-, from Proto-Germanic *un-, from Proto-Indo-European *n̥-. Cognate with Scots un-, on- (“un-”), North Frisian ün-, Saterland Frisian uun-, West Frisian ûn-, on-, Dutch on-, Low German un-, on-, German un-, Danish u-, Swedish o-, Norwegian u-, Icelandic ó-. More distant cognate with Latin in-, Ancient Greek ἀ- (a-) (whence English a-, modern Greek α- (a-)) and Sanskrit अ- (a-). Doublet of in- and a-.

Etymology 2

From Middle English on-, from Old English on-, ond-, and- (“against, facing, toward; in return, back, without”), from Proto-West Germanic *anda-, from Proto-Germanic *anda-, *andi- (“against”), from Proto-Indo-European *h₂énti (“across, forth, forward, ahead”), from *h₂énts (“end, limit, forehead”). In some cases the meaning is influenced by un- (“not”, etymology 1).

Etymology 3

From Latin ūnus.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.