Prefix | Meaning & Examples

A prefix is a letter or group of letters at the beginning of a root word (e.g., the “micro-” prefix in “micronutrient”). There are over 30 prefixes in the English language. Each prefix changes the meaning of a root word in a specific way. For example, if you add the “in-” prefix (meaning “not”) to “edible,” you get “inedible,” which means “not edible.”

Learning about English prefixes helps with reading comprehension and vocabulary. The prefix definitions and examples below show how a variety of prefixes affect the meaning of root words. If you want to learn more about prefixes, follow the links at the end for more prefix examples and a prefixes worksheet.

QuillBot’s free Grammar Checker can also help you with correct spelling when you use words with prefixes in your writing.

What is a prefix?

A prefix is an affix (a group of letters) at the beginning of a root word or base word. When you add a prefix to the beginning of a word, it changes the meaning. Unlike suffixes, prefixes do not change a word’s part of speech.

Most of the English prefixes were originally Latin prefixes (e.g., “dis-” and “extra”) or Greek prefixes (e.g., “mono-” and “anti-”).

In some cases, you can add different prefixes to the same root word. For example, “extraordinary” means “beyond ordinary,” but “unordinary” means “not ordinary.”

Prefix examples

The following chart includes some of the English words that begin with common prefixes. For more prefix examples, check out the QuillBot List of Prefixes, which is free to print or download

Metric prefixes (SI prefixes)

Metric prefixes go at the beginning of units of measurement (e.g., watts or hertz) and represent multiples or fractions of the base word. This International System of Units (SI prefixes) is used worldwide.

For example, the “giga-” prefix means “one billion” when the base word is a unit of measurement. If a laptop has 8 gigabytes of storage, it has 8 billion bytes.

Mega prefix

The “mega-” prefix has two slightly different uses and meanings. It means “one million” when it’s combined with a unit of measurement (e.g., “megabytes” or “megavolts”). When the base word isn’t a unit of measurement, the “mega-” prefix means “very large” (e.g., “megaphone”).

Prefixes and suffixes worksheet

To practice using prefixes (and suffixes) correctly, follow the link to print or download QuillBot’s free Prefixes and Suffixes Worksheet.

Frequently asked questions about prefixes

What are number prefixes?

Number prefixes are groups of letters at the beginning of a word that denote the quantity of the base word. For example, “bi-” means “two,” and a bicycle has two wheels (whereas a tricycle has three). The prefixes for each number are as follows:

1. Uni- or mono-
2. Bi- or di-
3. Tri-
4. Tetra-
5. Penta-
6. Hexa-
7. Hepta-
8. Octa-
9. Ennea-
10. Deca-

Words with number prefixes can be challenging to spell, but the QuillBot Grammar Checker will help you write them correctly.

What does the prefix in mean?

The prefix “in-” means “not.” It gives a root word the opposite meaning. For example, “inactivity” is the opposite of “activity.” Other words with the prefix “in” include “inaccurate,” “inedible,” and “incoherent” (e.g., “The rotten vegetables were totally inedible”).

Sometimes the prefix “in-” is confused with “un-” because they mean the same thing. Luckily, QuillBot’s free Grammar Checker can prevent those errors.

What does the prefix dis mean?

The prefix “dis-” means “stop” or “remove.” For example, when you add “dis-” to the verb “appear” to make “disappear,” it means that something stopped appearing. Other words with the prefix “dis” include “disengage,” “disassemble,” and “disobey.”

Spelling errors are common with long words that begin with “dis-,” such as “dissatisfaction” and “disassociation.” The QuillBot Grammar Checker instantly finds and fixes spelling errors.

Do English words have Greek prefixes?

Yes, English words have Greek prefixes, such as “mono-” in “monorail” and “monoculture” and “anti-” in “antibiotic” and “anticlimactic.” Some of the other Greek prefixes include:

• Auto- (e.g., automobile)
• Hyper- (e.g., hyperactive)
• Hypo- (e.g., hypothyroidism)
• Para- (e.g., paraprofessional)
• Tele- (e.g., telecommunications)

Have you tried QuillBot’s AI Chat for questions about word origins? It will instantly show you detailed and accurate responses to common grammar questions.

Do English words have Latin prefixes?

Yes, English words have Latin prefixes, such as “pre-” in “preview” and “prehistoric” and “in-” at the beginning of “inconceivable” and “inevitable.” Some of the other Latin prefixes include the following:

• Ab- (e.g., abnormal)
• De- (e.g., deactivate)
• Im- (e.g., impossible)
• Re- (e.g., regain)

QuillBot’s AI Chat can show you fascinating and detailed lists of English words with Latin prefixes.