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Compound adjectives

B2 Upper Intermediate

Compound adjectives are multi-word modifiers that function as a single unit to describe a noun. They often use hyphens to clarify meaning and prevent ambiguity when placed before a noun.

Overview

Compound adjectives combine two or more words to create a specific meaning that a single adjective cannot convey. They are most frequently formed by combining numbers with nouns, adjectives with nouns, or nouns with present or past participles. When these modifiers appear before the noun they describe, they are typically joined by a hyphen to show they function as one idea.

Form

Adjective/Noun/Number + Noun/Participle

The most common structures include:

  • Number + Noun: The noun must be in the singular form (e.g., a ten-minute break).
  • Adjective + Noun: Often used for physical descriptions (e.g., a long-term project).
  • Noun + Participle: Using either the -ing or -ed form (e.g., a mouth-watering meal, a sun-dried tomato).

Examples

Common mistakes

  • It was a five-miles walk.

    It was a five-mile walk.

    When a number and noun function as a compound adjective, the noun must be singular.

  • The project was very long term.

    The project was very long-term.

    While some style guides omit hyphens after the noun, B2 learners should use them for clarity in compound modifiers.

Hyphenated vs. Non-hyphenated

Hyphens are essential when the meaning might be confused. For example, a 'man-eating shark' is dangerous, but a 'man eating shark' is just a person having dinner.

PositionExampleRule
Before the nounA well-known actorUse a hyphen to link the words.
After the nounThe actor is well knownUsually, no hyphen is required.

Practice

  1. Rewrite the phrase using a compound adjective: 'A flight that lasts for six hours.'

    Show answer

    A six-hour flight

    Answer:A six-hour flight

    Why:The number and noun combine to modify 'flight'. The noun 'hour' must be singular and connected with a hyphen.

  2. Correct the error: 'We are staying in a five-stars hotel.'

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    We are staying in a five-star hotel.

    Answer:We are staying in a five-star hotel.

    Why:In a number-noun compound adjective, the noun (star) never takes a plural 's'.

  3. Choose the correct form: 'She is a (world famous / world-famous) scientist.'

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    world-famous

    Answer:world-famous

    Why:Because the adjective comes before the noun 'scientist', a hyphen is used to join the two parts of the compound.

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