Hyphens in Compound Adjectives

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Hyphens are used to link the words in compound adjectives to show they are single adjectives. For example:
  • two-seater aircraft
  • never-to-be-forgotten experience
(A compound adjective is a single adjective made up of more than one word.)
hyphens_compound_adjectives
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Hyphens in Compound Adjectives

The words in a compound adjective (a single adjective made up of two or more words) can be linked together by hyphens to show they are one grammatical unit (i.e., one multi-word adjective). For example:
  • I have sent you a three-page summary.
    • (The words in the compound adjective "three-page" are linked with a hyphen to show they are part of the same adjective.)
  • I have torn the ironing-board cover.
    • (The words in the compound adjective "ironing-board" are linked with a hyphen to show they are part of the same adjective.)

Compound Adjectives with Numbers

The easiest compound adjectives to spot are the ones that include numbers. For example:
  • Two-seater aircraft
  • 4-bedroom house
  • 45-minute journey
  • 15-page document
  • 5-and-a-half-year-old child
  • Three stone weakling
    • ("Three-stone" would be better.)
examples of hyphens in compound adjectives with numbers

Read more about numbers as compound adjectives.

Compound Adjectives Without Numbers

Lots of compound adjectives do not include numbers. For example:
  • Philip is a far-too-chatty individual.
  • That was a never-to-be-forgotten experience.
  • James is a second rate plumber.
    • ("Second-rate" would be better.)
Often, a compound adjective consists of words that would not normally be joined together with a hyphen. For example:
  • The double glazing is still leaking. Can you call that double-glazing salesman?
    • (The words "double glazing" only need a hyphen when they are functioning as an adjective. In this example, the first time they are used, they are not an adjective. The second time they are used, they are an adjective describing "salesman.")
  • You call this silver service? She's not a trained silver-service waitress.
    • (The second time they are used, the words "silver service" describe "waitress." As they are a compound adjective, they are linked with a hyphen to show they are a single adjective.)

How To Spot a Compound Adjective

Put "and" between the adjectives. If there is no loss of meaning, then you are likely dealing with several adjectives as opposed to a compound adjective. Let's try a few:
  • I have a large proud rooster.
    • (Is this a compound adjective? Do I need a hyphen?)
Step 1
Look at your adjectives:large proud rooster
Step 2
Put "and" between them:large and proud rooster
Step 3
Check the new wording:Although different in style, there is no loss of meaning. This is an example of two adjectives, not a compound adjective. Therefore, no hyphen is required.

large proud rooster
  • I have a free range rooster.
    • (Is this a compound adjective? Do I need a hyphen?)
Step 1
Look at your adjectives:free range rooster
Step 2
Put "and" between them:free and range rooster
Step 3
Check the new wording:In this example, there is a change in meaning. The rooster is not "free" and what is a "range rooster"? This is a compound adjective.

free-range rooster
  • I worked at a first aid post.
    • (Is this a compound adjective? Do I need a hyphen?)
Step 1
Look at your adjectives:first aid post
Step 2
Put "and" between them:first and aid post
Step 3
Check the new wording:Although "aid post" is okay, there is a change in meaning with "first post." This is a compound adjective.

first-aid post

The Hyphen Might Be Essential

Sometimes, a hyphen is essential to avoid ambiguity. Look at these examples:
  • a heavy-metal detector
  • a heavy metal detector
Both versions above are correct, but they mean different things. The first device detects heavy metals. The second device detects metal, and the device is heavy. If we're talking about a device that detects heavy metals, then writing "heavy metal detector" would be wrong because it is ambiguous. The hyphen is essential.

Don't Confuse Adverbs with Adjectives with Compound Adjectives

Adjectives are often preceded by adverbs like "very," "well," "beautifully," and "extremely."

Usually, there is no need to link an adverb to an adjective using a hyphen. For example:
  • Young Paula is a very talented student.
    • (As "very" is an adverb, it should not be linked to the adjective "talented" with a hyphen.)
Linking an adverb like "very," "most," or "least" to an adjective with a hyphen is an uncommon error. However, when an adverb ends in "-ly" (and lots do), some writers feel the urge to link it to the adjective with a hyphen. There is no need.
  • It is a wonderfully-decorated tree.
    • (The adverb "wonderfully" modifies the adjective "decorated," but there is no need to join the two with a hyphen.)
The following are not compound adjectives. No hyphens are required.
  • wonderfully-decorated tree
  • classically-trained pianist
  • happily-married couple
However, with words like "well," "fast," and "best" (which are both adjectives and adverbs), a hyphen can be used to avoid ambiguity.
  • Alan is the best-known player on the pitch.
    • (In this example, Alan is known better than any other player.)

  • Alan is the best known player on the pitch.
    • (This example could be taken to mean the same as the one above or it could be taken to mean that Alan is the best player of all the known players on the pitch. The hyphen eliminates ambiguity.)
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

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See Also

Alternatives to hyphens in compound adjectives Hyphens in prefixes Hyphens in compound nouns A list of common grammar errors A list of easily confused words A list of sayings and proverbs