Here are some examples of prefixes:
- microscope (The prefix is micro-.)
- tripod (The prefix is tri-.)
- devalue (The prefix is de-.)
The four most common prefixes account for over 95% of prefixed words. They aredis-, in-, re-, and un-.
When Do You Need a Hyphen with a Prefix?
Unfortunately, there is no simple rule governing this, but there are some guidelines.
Guiding Principles for Hyphens with Prefixes
If it's not a spelling mistake to avoid the hyphen and you can bear how the words looks without it, then avoid the hyphen.
Often, it's your choice whether to use a hyphen. Lots of prefixed words can be written with or without a hyphen. The underlying guideline is:
Try to avoid a hyphen with a prefix. However, if you feel the word looks too unwieldy without a hyphen or if your spellchecker highlights it as wrong, then add a hyphen.
- Antiaircraft (Antiaircraft is not wrong, but it looks a little unwieldy. If you feel the same way, go for anti-aircraft.)
The following words are all correct with or without a hyphen. Remember though, the guiding principle is avoid the hyphen if you can.
If your prefix sits before a proper noun, you should use a hyphen. Examples:
If the prefix ends in the same vowel that the root words starts with, separate them with a hyphen. Examples:
- coowner (Your spellchecker (or dictionary) will not let you have coowner.)
When a prefix ends in a vowel and the root word starts with a different vowel, it is usual to omit the hyphen. Examples:
- semiautonomous (However, if your spellchecker doesn't like it or you cannot bear how it looks, go for a hyphen. For many, semiautonomous looks too unwieldy.)
Use a Hyphen with Ex and Self
The prefixes ex and self are usually followed by a hyphen. Examples:
Eliminate Ambiguity Every Time
If the unhyphenated version could be confused with a different word, add the hyphen. (This is most common with the prefix re. Examples:
- re-cover / recover (If there were no hyphen in re-cover, it could be confused with recover, meaning return to a normal state.)
- re-press / repress (If there were no hyphen in re-press,Could be confused with repress, meaning subdue with force.)