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Home/Common Mistakes/Writing/Hyphens/Hyphenating prefixes

Hyphenating prefixes

Hyphenating prefixes correctly is not easy. There are some rules and some personal choices.

Use a hyphen with these prefixes:

  • all-
  • cross-
  • ex-
  • self-
  • co-
  • semi-
  • anti-

As in these examples:

  • all-conquering team
  • cross-country runner
  • ex-girlfriend
  • self-service
  • co-owner
  • semi-circular
  • anti-aircraft gun

Hyphens are used before a proper noun.

  • trans-Siberian train
  • un-English

Hyphens are used before a number.

  • mid-1990s
  • pre-20th century

Hyphens are used before an abbreviation.

  • non-ISO compliant
  • pre-COVID-19

Hyphens are used when the prefix ends with the same vowel that the base word being connected to it begins with.

  • re-enter
  • ultra-aggressive

Hyphens are used to make the meaning of the word clear.

  • Co-op
    (The short form of co-operate.)
    (A place to keep chickens.)
  • Re-sign
    (To sign again.)
    (To leave your job.)
  • Man eating shark.
    (A man is eating a shark.)
    Man-eating shark.
    (A shark that eats people.)
  • She has a concealed gun licence.
    (You her cannot see her gun licence.)
    She has a concealed-gun licence.
    (She has a licence to carry concealed guns.)

If the word is easy to read without a hyphen, don’t use one. If it is difficult to read put one in. These examples show when personal choice can be used.

  • The story is set in prewar England.
    The story is set in pre-war England.
  • Should I restart the car.
    Should I re-start the car.
  • The soldiers were using their new infrared glasses.
    The soldiers were using their new infra-red glasses.

Your choice.