A prefix is a group of letters that can be added to the beginning of a word (‘pre‘ means ‘in front of’). Adding a prefix changes the meaning of the word. Some examples of prefixes are: un, dis, in, im, il, and ir.

Here are some common prefixes you should know.

By adding a prefix you can change the word to the opposite meaning.


Adding a prefix is easy. However, if the last letter of the prefix is the same as the first letter of the root word, keep both letters.


Here are some more opposites formed by adding un, in, im, or dis.

Note: The main part of a word is its root. The root word has its own meaning. When added to a prefix it gives the word its backbone of meaning. Many words in English language have its origin in other languages; a larger number of words have their origins in Latin and Greek roots. Knowing many of these will help you determine their meanings.

Here are 50 Greek and Latin root words that can help you boost your vocabulary skills.


Hyphen with Prefixes

Ordinarily, a hyphen is not used to join a prefix to a word. There are few exceptions. You should always consult you dictionary if you are in doubt.

Following are the exceptions:

  1. Use a hyphen after any prefix joined to a proper noun or adjective. Use a hyphen after prefixes all-, ex– and self-.
  2. Use a hyphen after the prefix anti– when it joins a word beginning with i. Use a hyphen after the prefix vice-, except in vice president.
  3. Use a hyphen to avoid confusion between words, like re-.


Prefixes – ‘im’ and ‘in’