Summary
A prefix is a letter or group of letters added to the beginning of a root word. Prefixes have set meanings and change the meaning of the root word when combined.
In-depth Explanation
Prefixes are not words on their own. They must be attached to the front of a root word. For example:
inter- (prefix) + national (root word) = international
The prefix inter- means “between” or “among.” The new word, “international,” means “between nations.” For example:
The conference attracted international participants from over 20 countries.
Most Common Prefixes
Here are some of the most common English prefixes, their meanings and examples:
| Prefix | Meaning | Examples |
| anti- | against | antibiotic antisocial antiwar |
| de- | opposite; down | defrost depart descend |
| dis- | not; opposite | disagree dissimilar disobey |
| il- / im- / in- / ir- | not | illegal impossible insane irregular |
| inter- | between | interact internet interconnected |
| mis- | wrongly; badly | misplace misspell misuse |
| non- | not | nonfiction nonprofit nonstop |
| pre- | before | prefix preheat preview |
| re- | again | rediscover redo reread |
| sub- | under | submarine submit subway |
| un- | not; opposite | unable uncommon unhappy |
| under- | below; too little | undercooked underestimate underground |
Here are some examples of how words with prefixes are used in context:
The train will depart at 9 a.m.
Be careful not to misspell words in your essay.
The plane flew nonstop from New York to London.
Remember to preheat the oven before baking.
The chicken was undercooked and not safe to eat.
Prefixes with Hyphens
There are some prefixes that need a hyphen between the prefix and the root word. For example:
| Prefix | Meaning | Examples |
| all- | all | all-inclusive all-knowing all-powerful |
| ex-* | previous | ex-boyfriend ex-colleague ex-president |
| self- | to, of or by one’s self | self-control self-employed self-taught |
*The prefix ex- can also appear in words without a hyphen, in which case it means “out of” or “from.” For example: exit, extend, export. A prefix also needs a hyphen when the root word is a proper noun, like in “mid-July.”
Here are some examples of these prefixes in context:
The professor seemed all-knowing, able to answer any question we asked him.
She had an awkward encounter with her ex-boyfriend at the coffee shop last weekend.
It took a lot of self-control to resist eating the entire cake.
Prefixes in Unpaired Words
Some root words must have a prefix in order to be considered an English word. These are called unpaired words. Some common examples are:
- disrupt
- predict
- reduce
If you remove the prefix from each word above, they are no longer words: rupt, dict, duce. In these cases, the meaning of the prefix can still help you understand the meaning of the word.
For instance, pre- means “before.” “Predict” means to say that something will happen in the future. In other words: You guess what will happen before it happens.