The hyphen (-) is a small punctuation mark with an important role in English writing. It is mainly used to connect words or word parts so that meaning is clear and unambiguous. Because hyphens are often confused with other dashes or misused in compound expressions, understanding their correct usage is essential for accurate and natural English.
Hyphen
A hyphen (-) is a punctuation mark used to join words or parts of words. It commonly appears in compound adjectives, some compound words, and with certain prefixes.
Unlike longer dashes, the hyphen is short and written as a single horizontal line.
Examples:
- a well-known author
- a part-time job
- a self-aware student
Hyphen vs. En Dash vs. Em Dash
| Mark | Name | Main Function | Example |
|---|---|---|---|
| – | Hyphen | Joins words or word parts | a well-known rule |
| – | En Dash | Shows ranges or connections | 2007–2008 |
| — | Em Dash | Indicates a pause or break in thought | She was late — again. |
Visually, the hyphen is the shortest, the en dash is slightly longer, and the em dash is the longest.
Hyphen Usage
When to Use a Hyphen
Compound Adjectives
Use a hyphen when two or more words work together as a single adjective before a noun.
- a well-known politician
- an easy-to-understand explanation
- an off-campus apartment
Important rule: When the adjective comes after the noun (often after a verb like to be), do not use a hyphen.
- The politician is well known.
- The apartment is off campus.
Adverbs Ending in -ly
Never use a hyphen after an adverb ending in -ly. These adverbs already clearly modify the adjective that follows.
- a beautifully decorated room (NOT beautifully-decorated)
- a highly respected teacher
Some Compound Words
English compound words can be open (no hyphen), hyphenated, or closed. Not all compound nouns need a hyphen.
- soup bowl (open compound)
- mother-in-law (hyphenated compound)
- notebook (closed compound)
Hyphen use in compound nouns often depends on convention and dictionary usage.
Prefixes
Most prefixes do not need a hyphen. Use a hyphen only in specific cases:
- With prefixes like self-, ex-, all-: self-control, ex-president
- Before a proper noun: anti-American
- To avoid confusion or repeated vowels: re-enter
Numbers and Fractions
When numbers from 21 to 99 are written in words, they always require a hyphen.
- twenty-five students
- ninety-nine problems
- a two-year-old child
- a one-third share
When a Hyphen Is NOT Needed
- Compound adjectives after a noun: The rule is well known.
- Most prefixed words: reuse, rewrite, preview.
- Open compound nouns: living room, coffee table, soup bowl.
Last Updated on February 4, 2026
