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To begin your search, go to the alphabetical index below and click on the first letter of the word you are searching for.

non-, un-

Although both of these prefixes negate the meaning of the word they are attached to, there is a distinction in meaning between them.


The prefix non- means “other than.” In most cases, it has a neutral connotation.

  • I made a non-alcoholic punch for the party.
  • All of the plants in my terrarium are non-poisonous.
  • Don’t talk such nonsense!

Note: Avoid using this prefix to create new words when a suitable opposite already exists:

  • inaudible, not non-audible
  • disagreement, not non-concurrence
  • temporary, not non-permanent


The prefix un‑ means “the opposite of.”

  • Check an unabridged dictionary for the definition.
  • When unbuttoned, the jacket was loose.

When attached to a positive word, un‑ often gives a negative connotation.

  • The man’s behaviour was unnatural.
  • Her remarks were very uncharitable.

Non- vs. un-

The distinction in meaning between these two prefixes can be seen in the following pairs of examples:

  • non-scientific: not connected with science (neutral)
    unscientific: lacking scientific rigour (negative)
  • non-Christian: not connected with Christianity (neutral)
    un-Christian: not befitting a Christian (negative)
  • non-Canadian: not connected with Canada (neutral)
    un-Canadian: not befitting a Canadian (negative)
  • non-serviceable: not meant to be serviced (neutral)
    unserviceable: so worn that it can no longer be brought back into service (negative)