A hyphen (-) is a punctuation mark used to join words or parts of words. It appears in expressions such as well-known, twenty-five, and mother-in-law.
Sometimes a hyphen makes an important difference to meaning.
Compare:
The director asked her to re-sign the agreement.
The director asked her to resign.
The first sentence means signing an agreement again. The second means leaving a position.
But not every compound word needs a hyphen. Some are written as one word, others as separate words, and some change their spelling depending on how they’re used in a sentence.
Hyphens in Compound Modifiers
A compound modifier consists of two or more words working together to describe something. A hyphen can show that the words belong together rather than describe the noun separately.
Before and After a Noun
When a compound modifier comes before a noun, it often takes a hyphen.
For example:
The committee interviewed a well-prepared witness.
Here, well-prepared describes the witness as a single idea.
Now move the description after the noun:
The witness was well prepared.
The hyphen is normally unnecessary because the sentence makes the relationship between the words clear.
Another example:
They installed a noise-reducing barrier beside the highway.
In this sentence, noise-reducing works as one modifier describing the barrier.
However, the before-and-after rule has exceptions.
Some established compounds retain their hyphens even when they follow a noun.
Compare:
The company proposed a cost-effective repair.
The proposed repair was cost-effective.
Cost-effective is conventionally hyphenated in both positions.
The position of a modifier is therefore a useful starting point, but it doesn’t override established spelling.
For a closer explanation of these constructions, see compound modifiers and hyphenation.
When a Compound Modifier Doesn’t Need a Hyphen
Not every pair of words describing a noun should be joined.
One important exception involves adverbs ending in -ly.
Compare:
The laboratory hired a highly qualified technician.
The technician submitted a carefully written report.
You don’t normally hyphenate highly qualified or carefully written.
The -ly adverb already makes its relationship with the following adjective or participle clear.
This differs from:
The laboratory hired a well-qualified technician.
Here, well doesn’t end in -ly, and the hyphen is commonly used when the expression appears before the noun.
But the rule concerns adverbs ending in -ly, not every word that happens to end with those letters.
For example:
The hotel opened a family-friendly restaurant.
Family is a noun, not an -ly adverb. The compound adjective family-friendly is conventionally hyphenated.
A hyphen is also unnecessary when two adjectives independently describe a noun.
She bought a beautiful wooden cabinet.
Beautiful and wooden describe the cabinet in different ways. They don’t form one compound modifier.
Hyphenated, Open, and Closed Compound Words
Compound words combine words or other meaningful elements, but English doesn’t write every compound in the same way.
There are three common forms.
| Form | How it’s written | Examples |
|---|---|---|
| Open compound | Separate words | post office, swimming pool |
| Closed compound | One word | notebook, greenhouse |
| Hyphenated compound | Joined with hyphens | mother-in-law, editor-in-chief |
Bedroom is normally one word, dining room is written as two, and mother-in-law uses hyphens.
Some titles also have established hyphenated spellings.
The president-elect addressed the committee.
The editor-in-chief approved the revised manuscript.
President-elect refers to someone elected to an office but not yet serving in it. Editor-in-chief is a compound title with its own established spelling.
When the Same Words Have Different Forms
Some expressions change their spelling because they perform different grammatical jobs.
Consider check in and check-in.
Verb:
Guests can check in at reception after 2 p.m.
Here, check in is a phrasal verb.
Noun:
Online check-in closes two hours before departure.
Here, check-in is a noun.
The same distinction appears in other familiar expressions:
Please follow up with the supplier tomorrow.
The supplier requested a follow-up meeting.
In the first sentence, follow up is a verb phrase.
In the second, follow-up functions as a compound modifier describing the meeting.
What If Dictionaries Show Different Spellings?
You may encounter more than one accepted form of a compound word.
English spelling changes over time. Some expressions that were once commonly hyphenated eventually become closed compounds. Others remain hyphenated or open.
Regional preferences and editorial styles can also differ.
For ordinary writing, use a current, reliable dictionary as your starting point. If you’re writing for a publication that follows a particular style guide, check its conventions as well.
When two spellings are accepted, consistency is generally more useful than switching forms throughout the same document.
Hyphens with Numbers, Ages, and Fractions
Numbers have several common hyphenation patterns. The important distinction is often between a number written as a word and a number-based expression used to describe a noun.
Compound Numbers
When spelling out numbers from twenty-one through ninety-nine, use a hyphen between the tens and units.
For example:
Twenty-seven volunteers registered for the coastal cleanup.
The collection included sixty-four handwritten letters.
Larger numbers can contain these hyphenated parts:
The charity received one hundred and forty-eight donations.
Here, forty-eight remains hyphenated.
The use of and in larger spelled-out numbers can vary between American and British English, but the hyphen in forty-eight follows the same general convention.
Ages and Measurements
When an age or measurement forms a compound modifier before a noun, hyphens commonly join the words.
Compare:
The museum restored a 200-year-old painting.
The painting is 200 years old.
In the first sentence, 200-year-old works as one description before painting.
The word year remains singular within the compound modifier.
In the second sentence, 200 years old follows the noun and isn’t written as a hyphenated compound.
The same pattern appears with measurements:
The workers installed a six-foot fence.
The fence is six feet tall.
And with time:
They signed a three-year contract.
The contract lasts three years.
Notice the singular unit in the compound modifier: six-foot, three-year, and 200-year-old.
A common mistake is writing a three-years contract. The unit should be singular in this construction.
When a measurement uses an abbreviated unit, conventions differ. Some technical styles write a 10 km route without a hyphen, while others use a hyphenated form.
Follow the style required for your document rather than assuming one convention applies everywhere.
Fractions
Spelled-out fractions often take hyphens.
For example:
One-third of the applicants had previous experience.
The recipe calls for two-thirds of a cup of milk.
Some editorial styles allow open forms in certain contexts, so the preferred spelling may depend on the publication.
Not every expression involving a fraction needs a hyphen:
A third of the applicants had previous experience.
Here, a third is an ordinary noun phrase.
A spelled-out fraction can also function as a modifier before another noun:
The proposal received a two-thirds majority.
Numerical fractions such as 1/3 and 2/3 don’t normally need additional hyphens, although their presentation may depend on the document’s style.
Hyphens with Prefixes
Prefixes attach to the beginning of words. Some are normally written without hyphens, while others commonly take them.
When a Hyphen Changes the Meaning
Sometimes a hyphen distinguishes two words that would otherwise look alike.
Compare:
The manager asked the contractor to re-cover the damaged chairs.
The insurance company expects the contractor to recover the costs.
Re-cover means to cover something again.
Recover can mean to regain something, return to a previous condition, or obtain something that was lost.
Prefixes That Commonly Take Hyphens
Some prefixes are regularly hyphenated in standard English spelling.
Self-
She completed a self-assessment before the annual review.
The course encourages self-directed learning.
Ex- meaning former
The former chairperson met with the ex-president of the association.
Her ex-husband attended the family celebration.
Prefixes attached to proper names
The exhibition included several pre-Roman artifacts.
The documentary explored anti-American sentiment during the period.
A hyphen commonly separates the prefix from the capitalized proper name.
However, many other prefixes usually form closed words.
For example:
unhappy
rewrite
misplace
nonprofit
It’s unnecessary to add a hyphen to every word beginning with a prefix.
What About Repeated Vowels?
You may see both hyphenated and closed forms when a prefix ends with the same vowel that begins the next part of the word.
For example:
re-enter / reenter
pre-existing / preexisting
The preferred spelling depends on the word, dictionary, and editorial style.
Other words, such as cooperate, are commonly written without a hyphen.
There is no universal rule requiring a hyphen whenever two vowels meet.
Checking the established spelling is more reliable than counting repeated letters.
Less-Obvious Uses of Hyphens
Suspended Hyphens
Sometimes two compound modifiers share the same final word.
Instead of repeating that word, you can leave the first hyphen in place to show that something has been omitted.
For example:
The museum offers one- and two-hour guided tours.
This means the museum offers both one-hour and two-hour tours.
The hyphen after one- indicates that hour has been omitted from the first compound.
Another example:
The company reviewed its short- and long-term staffing needs.
This means short-term and long-term staffing needs.
This construction is called a suspended hyphen.
It’s an optional way to avoid repetition, not a requirement.
You could also write:
The museum offers one-hour and two-hour guided tours.
Repeating the full expressions is often easier to read, especially when the shared words aren’t immediately obvious.
Hyphens Are Different from Dashes
A hyphen (-) joins words or word parts. An en dash (–) and an em dash (—) have different punctuation functions.
Compare:
The company introduced a six-month training program.
The exhibition runs from May to September.
The exhibition runs May–September.
The first sentence uses a hyphen in a compound modifier.
The final example uses an en dash to indicate a range. When the range is written with from, the corresponding word is to, not a dash.
Hyphens and dashes aren’t interchangeable.
For a full comparison, see hyphen vs. dash.
Hyphens at the End of a Line
A word may be divided between two lines with a hyphen in typeset text. This is called word division, and many word processors handle it automatically.
The inserted hyphen isn’t necessarily part of the word’s normal spelling and may disappear when the complete word fits on one line.
How to Decide When a Hyphen Is Needed
Not every uncertain expression can be resolved by the same rule.
Sometimes the sentence structure makes the appropriate choice clear. Other times, you need to know how the word is conventionally spelled.
When the Hyphen Clarifies the Meaning
Imagine you’re editing a company’s recruitment announcement:
We’re looking for a small business consultant.
Without the hyphen, readers may initially be unsure whether small describes the consultant or forms part of small business.
If the company wants someone who advises small businesses, a hyphen can make the relationship clearer:
We’re looking for a small-business consultant.
Here, small-business works as one modifier of consultant.
You could also rewrite the sentence:
We’re looking for a consultant who specializes in small businesses.
This version makes the intended meaning explicit without relying on punctuation to resolve the ambiguity.
When Established Spelling Determines the Choice
Now consider:
The organization offers support for employee well being.
Should you write well being, wellbeing, or well-being?
This isn’t simply a question of whether the expression comes before or after a noun.
Well-being is an established compound noun, and dictionaries or editorial styles may differ in their preferred spelling.
Well-being is a common dictionary form, while wellbeing also appears in some dictionaries and publication styles.
If your publication uses well-being, write:
The organization offers support for employee well-being.
The choice follows the spelling convention being used, not the rule about compound modifiers before nouns.
If a long compound modifier remains difficult to understand, rewriting the sentence may be clearer than trying to join every descriptive word with hyphens.
Practice: Choose the Correct Form
These exercises involve common hyphenation decisions. Some require a definite correction, while others ask you to recognize the difference between a spelling rule and an accepted variation.
Exercise 1: Before or After the Noun?
Choose the appropriate forms.
A.
The committee selected a well qualified applicant.
B.
The applicant was well-qualified for the position.
Answer
A.
The committee selected a well-qualified applicant.
The compound modifier comes before applicant, so the hyphen is normally appropriate.
B.
The applicant was well qualified for the position.
The description follows the noun and linking verb, so the hyphen isn’t normally needed.
Exercise 2: Log In or Login?
Complete these sentences using the appropriate form of log in.
A.
Please ______ to your account before the online examination begins.
B.
The ______ page requires a six-digit security code.
Answer
A.
Please log in to your account before the online examination begins.
Log in functions as a phrasal verb, so it is written as two words.
B.
The login page requires a six-digit security code.
Here, login functions as a noun modifying page. The closed form is common in computing contexts.
Exercise 3: Re-form or Reform?
The words re-form and reform have different meanings.
Choose the correct spelling for each sentence.
A.
After several years apart, the musicians decided to ______ their original band.
B.
The government introduced new measures to ______ the outdated education system.
Answer
A.
After several years apart, the musicians decided to re-form their original band.
Re-form means to form something again. Here, the musicians are bringing their former band back together.
B.
The government introduced new measures to reform the outdated education system.
Reform means to improve or change something, especially an institution or system.
The hyphen makes the distinction clear.
Exercise 4: Ages and Measurements
Correct the hyphenation and number forms where needed.
A.
The charity launched a three-years program for new volunteers.
B.
The program lasts three-years.
C.
They renovated a 150 year old farmhouse.
Answer
A.
The charity launched a three-year program for new volunteers.
The compound modifier comes before program, and year remains singular.
B.
The program lasts three years.
The time expression follows the verb and isn’t a compound modifier.
C.
They renovated a 150-year-old farmhouse.
The complete age expression modifies farmhouse, so hyphens join its parts.
Exercise 5: Suspended Hyphens
A training provider offers courses lasting either six weeks or twelve weeks.
Rewrite the following sentence using a suspended hyphen. Is the original version also correct?
Original:
The provider offers six-week and twelve-week courses.
Answer
The provider offers six- and twelve-week courses.
The hyphen after six- shows that week has been omitted from the first compound.
The original version is also correct.
The provider offers six-week and twelve-week courses.
The suspended-hyphen construction is optional. Either version is suitable, provided the meaning is clear.
If a hyphenation choice still feels uncertain, you don’t have to force every expression into one rule. Sometimes a dictionary settles the spelling. Other times, looking at how the words work together, or rewriting the sentence, gives you a clearer answer.
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