Hyphen (-)

Hyphens are used to link words and parts of words. They are not as common today as they used to be, but there are three main cases where you should use them:

Hyphens in compound words

Hyphens are used in many compound words to show that the component words have a combined meaning (e.g. a pick-me-up, mother-in-law, good-hearted) or that there is a relationship between the words that make up the compound: for example, rock-forming minerals are minerals that form rocks. But you don’t need to use them in every type of compound word.

Compound adjectives

Compound adjectives are made up of a noun + an adjective, a noun + a participle, or an adjective + a participle. Many compound adjectives should be hyphenated. Here are some examples:

noun + adjective

noun + participle

adjective + participle

accident-prone

computer-aided

good-looking

sugar-free

power-driven

quick-thinking

carbon-neutral

user-generated

bad-tempered

sport-mad

custom-built

fair-haired

camera-ready

muddle-headed

open-mouthed

 

With compound adjectives formed from the adverb well and a participle (e.g. well-known), or from a phrase (e.g. up-to-date), you should use a hyphen when the compound comes before the noun:

well-known brands of coffee

an up-to-date account

but not when the compound comes after the noun:

His music was also well known in England.

Their figures are up to date.

It’s important to use hyphens in compound adjectives describing ages and lengths of time: leaving them out can make the meaning ambiguous. For example, 250-year-old trees clearly refers to trees that are 250 years old, while 250 year old trees could equally refer to 250 trees that are all one year old.

Compound verbs

Use a hyphen when a compound formed from two nouns is made into a verb, for example:

noun

verb

an ice skate

to ice-skate

a booby trap

to booby-trap

a spot check

to spot-check

a court martial

to court-martial

Phrasal verbs

You should NOT put a hyphen within phrasal verbs - verbs made up of a main verb and an adverb or preposition. For example:

Phrasal verb

Example

build up

You should continue to build up your pension.

break in

They broke in by forcing a lock on the door.

stop off

We stopped off in Hawaii on the way home.

 

If a phrasal verb is made into a noun, though, you SHOULD use a hyphen:

Noun

Example

build-up

There was a build-up of traffic on the ring road.

break-in

The house was unoccupied at the time of the break-in.

stop-off

We knew there would be a stop-off in Singapore for refuelling.

Compound nouns

A compound noun is one consisting of two component nouns. In principle, such nouns can be written in one of three different ways:

one word

two words

hyphenated

aircrew

air crew

air-crew

playgroup

play group

play-group

chatroom

chat room

chat-room

 

In the past, these sorts of compounds were usually hyphenated, but the situation is different today. The tendency is now to write them as either one word or two separate words. However, the most important thing to note is that you should choose one style and stick to it within a piece of writing. Don’t refer to a playgroup in one paragraph and a play-group in another.

Hyphens joining prefixes to other words

Hyphens can be used to join a prefix to another word, especially if the prefix ends in a vowel and the other word also begins with one (e.g. pre-eminent or co-own). This use is less common than it used to be, though, and one-word forms are becoming more usual (e.g. prearrange or cooperate).

Use a hyphen to separate a prefix from a name or date, e.g. post-Aristotelian or pre-1900.

Use a hyphen to avoid confusion with another word: for example, to distinguish re-cover (= provide something with a new cover) from recover (= get well again).

Hyphens showing word breaks

Hyphens can also be used to divide words that are not usually hyphenated.

They show where a word is to be divided at the end of a line of writing. Always try to split the word in a sensible place, so that the first part does not mislead the reader: for example, hel-met not he-lmet; dis-abled not disa-bled.

Hyphens are also used to stand for a common second element in all but the last word of a list, e.g.:

You may see a yield that is two-, three-, or fourfold.

You can read more about when to use hyphens on the Oxford Dictionaries blog. Here you will find helpful tips on when to use hyphens and examples of when they should not be used.

 

Back to punctuation.

You may also be interested in

Exclamation mark (!)

Question mark (?)

Dash (–)


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