What is a hyphen?
- A hyphen (-) is a punctuation mark that’s used to join words or parts of words. It’s not interchangeable with the various dashes.
- Hyphens are often used in compound modifiers when the modifier comes before the word it’s modifying.
- If you’re not sure whether a compound word has a hyphen, check your preferred dictionary.
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Table of contents
Hyphens with compound modifiers: Multiple-word adjectives before nouns
Hyphens and compound modifiers with participles
Hyphens and compound words
Closed compound words
Open compound words
Hyphens and numbers
Hyphens with prefixes: Ex-, self-, all-
Hyphens with compound modifiers: Multiple-word adjectives before nouns
Using hyphens to connect words is easy. Picking the right words to connect is a little harder. Let’s start with compound modifiers, also known as phrasal adjectives.
A compound modifier is made up of two or more words that work together to function like one adjective in describing a noun. When you connect words with a hyphen, you make it clear to readers that the words work together as a unit of meaning.
It’s recommended you don’t take down any load bearing walls when renovating.
It would be easy to read the above sentence as saying that you shouldn’t take down any load that is holding up a wall. A hyphen should be inserted between load and bearing to make it clear that we’re talking about walls that are bearing a load.
It’s recommended you don’t take down any load-bearing walls when renovating.
This rock-hard cake is absolutely impossible to eat.
We’re looking for a dog-friendly hotel.
She makes one-of-a-kind engagement rings in her studio.
The new house has state-of-the-art features.
Generally, you need the hyphen only if the two or more words are functioning together as an adjective before the noun they’re describing. If the noun comes first, we usually leave the hyphen out.
This wall is load bearing.
It’s impossible to eat this cake because it is rock hard.
Is this hotel dog friendly?
You never use a hyphen when your modifier is made up of an adverb ending in -ly and an adjective.
Do you expect me to believe this clearly-impossible story?
Do you expect me to believe this clearly impossible story?
Hyphens and compound modifiers with participles
Compound modifiers that include present or past participles follow the same rules as any other compound modifier.
Hyphens in compound modifiers with present participles
When we combine an adjective, a noun, or an adverb that doesn’t end in -ly with a present participle (the –ing form of a verb) to describe another word, we use a hyphen to make the meaning of the combined descriptor clear.
There are some beautiful looking flowers in the garden.
Without the hyphen between beautiful and looking, your reader may stumble over the sentence. Perhaps there’s a new type of daisy called the “looking flower”?
There are some beautiful-looking flowers in the garden.
Fast-acting medication can be useful when one has a headache.
The belt-tightening measures at the company included some layoffs.
I prefer a forward-facing seat on the train.
Don’t use a hyphen when the modifier comes after the noun it’s describing.
This medication is fast acting.
Don’t use a hyphen when you are combining an adverb ending in -ly and a participle.
The room was like a heavily-decorated chocolate box.
The room was like a heavily decorated chocolate box.
Hyphens in compound modifiers with past participles
Compound modifiers that contain a past participle follow the same rules as other compound modifiers. Use a hyphen when the compound goes before the noun it modifies:
The municipal government is funding a community-based education system.
Wind-powered generators can be excellent sources of electricity.
Many veterinarians find meat-fed cats to be quite healthy.
A well-known local singer will perform tonight.
Don’t use a hyphen when the compound comes after the noun it describes.
The singer performing tonight is well known.
Hyphens with high and low
When using high or low as part of a compound modifier, use a hyphen when the compound comes before the noun it’s modifying.
Low-flying airplanes contribute to the noise pollution in the area.
This car runs best on high-octane gasoline.
Low-income families often face more stress than their higher-income counterparts.
A high-interest savings account is one of the best ways to save money.
Hyphens and compound words
Hyphenated compound words are multi-word terms with a hyphen or hyphens between their component words. Over time, many hyphenated compounds become closed compounds—teen-ager became teenager, for instance. Check a dictionary if you’re not sure how to treat a compound. Here are a few examples of common hyphenated compound words:
Mother-in-law
Half-pipe
Ten-year-old
Six-pack
Foot-pound
President-elect
Closed compound words
Hyphenated words tend to become closed compounds (single words, with no spaces and no hyphens) over time. Email instead of e-mail, for example, is increasingly common. If you aren’t sure whether a word is a closed compound or a hyphenated one, check your preferred dictionary.
Notebook
Halftime
Waistcoat
Fundraiser
Chairperson
Open compound words
Open compounds are typically made up of two nouns that are used together to represent a single idea. “Open” means that there is a space between the two words and no hyphen. Again, a good dictionary is the best place to find out how to treat compounds—if the compound isn’t in the dictionary, that means it should be open.
Living room
Real estate
Dinner table
Home base
Hyphens and numbers
Numbers between twenty-one and ninety-nine should be hyphenated when they’re spelled out.
My parents arrived in Bratislava twenty-four hours ago.
This is the eighty-first baseball game of the regular season.
I’ve got ninety-two of these gizmos to sell.
Spelled-out two-word simple fractions are also hyphenated. One-word simple fractions (such as half and quarter) as part of a compound are not joined by hyphens to the other word or words of the compound in its noun form, however.
I’ve seen about one-third of the movies on the AFI’s list.
We’ve been sitting here for about a half hour.
Hyphens in compound modifiers involving numbers
When a number appears as the first part of a compound modifier that comes before a noun in a sentence, the compound modifier is hyphenated. This applies whether the number is spelled out or in numerals, and whether it is cardinal or ordinal.
The president of the company gave a ten-minute speech to the board of directors.
The shopping mall installed a 107-foot-tall LED tower.
He is knowledgeable about thirteenth-century politics.
The kid threw a rock at the second-story window.
However, a hyphen is not required if the number is the second word in the compound adjective.
She has type 2 diabetes.
There’s no basem*nt 3 button in this elevator because it doesn’t go down that far.
Hyphens are also not used between a number and the word percent appearing before a noun.
The channel got a 90 percent bump in subscribers after the video went viral.
Hyphens in compound modifiers involving fractions
When a fraction (e.g., half or quarter) is used as part of a compound adjective appearing before a noun, it should be hyphenated.
I went on a three-quarter-mile run yesterday.
They pitched an idea for a half-hour comedy to the network.
The word half also combines with other words to form compounds in nonmathematical contexts. These compounds are generally hyphenated when they are used as adjectives (before or after a noun) and open when they are used as nouns or verbs.
She managed to salvage quite a bit of the half-burned sauce.
I was only half-awake when I answered your call.
He made a half attempt to contribute to the conversation, but he didn’t really mind just listening to the others.
They half wished for a live-in assistant.
Hyphens with prefixes: Ex-, self-, all-
Use a hyphen with the prefix ex- (meaning former).
Don’t seat Masami and Ira next to each other! They are ex-partners!
Though she no longer held an official position, the ex-mayor still attended all the town’s functions.
Use a hyphen with the reflexive prefix self-.
Lying on the floor beside the plant he had knocked over and chewed on, the cat looked extremely self-satisfied.
The famous artist’s self-absorption was often noted.
When using all as part of a compound, use a hyphen if the compound is adjectival and leave the compound open if it is adverbial.
It’s a bad leader who thinks of themself as all-powerful.
The team went all in to meet the deadline for their project.
