Compound adjectives with numbers: ‘a two-day trip’

Compound adjectives with numbers: Grammar chart

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Adjectives

Adjectives are words used before a noun or after the verb be or a verb of the senses (feel, look, smell, sound, taste) to describe something.

• They have an expensive car.
• Your idea is fantastic. 
• John looks tired.

Compound adjectives

Compound adjectives are made of two or more words: a well-dressed man, a part-time job, a first-class train ticket, etc.

We should join the different words in a compound adjective with a hyphen to show that they go together and are part of the same idea.

Number + noun

We can use number + noun as a compound adjective before another noun.

This construction is often used with nouns of measurement, such as foot, metre, mile, pound, kilogram, second, minute, hour, pound, dollar, etc..

There are two things that you should remember about number-noun compound adjectives:

Use a singular noun. Remember adjectives have no plural form in English:

• A two-days journey
• A two-day journey

Use a hyphen to connect the number to the noun that follows it. This allows the reader to know that both words function as a unit that modifies the noun after it:

• A 30-minute show
• A two-day journey
• A 50-metre pool
• An eight-core processor
• A two-bedroom apartment

🔍 Note that you can write metre, litre (UK spelling) or meter, liter (US spelling).

Sometimes, a compound adjective is made up of more than one word:

• A 10-million-dollar house
• A seven-year-old child

Number + part of the body + -ed

When we use a number + noun as a compound adjective, and the noun is a part of the body, then we have to add -ed after the part of the body.

• A three-legged table
• A seven-headed dragon
• A one-eyed alien
• A four-armed robot

❗ Note that the consonant is doubled when the last syllable of the noun is stressed and is made of consonant + vowel + consonant: legged.