A compound noun is a noun that is made with two or more words. A compound noun is usually [noun + noun] or [adjective + noun], but there are other combinations (see picture). It is important to understand and recognize compound nouns. Each compound noun acts as a single unit and can be modified by adjectives and other nouns.
There are three forms for compound nouns:
• open or separated — space between words (eg.: tennis shoe)
• hyphenated — hyphen between words (eg.: six-pack)
• closed or solid — no space or hyphen between words (eg.: bedroom)
Sometimes compound nouns are written separately (eg.: nail polish), sometimes with a hyphen (eg.: short-sighted) and sometimes as one word (eg.: eyelashes). Often new compounds are written as two separate words and, as they become more familiar, they are either connected with a hyphen (-) or made into one word.
There are some general rules and guidelines for when to use hyphens:
– when there is a prefix
– when a compound adjective comes before a head noun
• a well-known singer
• an angry-sounding email
• an English-speaking country
– when the pre-head item in a compound is a single capital letter
– when words are difficult to recognise as compounds and could be confused
• The band has decided to re-form. (form again)
• The Government promise to reform the health system. (improve)
– when compound adjectives containing numbers appear before a noun
• A twenty-two-year-old cyclist won the race.
• From here to Jakarta, that’s a twelve-hour flight at least.
How do we make compound nouns plural?
In general we make the plural of a compound noun by adding -s to the base word (the most significant word).
• assistant headmaster — assistant headmasters
• mother-in-law — mothers-in-law
• assistant secretary of state — assistant secretaries of state
• woman-doctor — women-doctors
• passer-by — passers-by
Note that there is some variation with words like spoonful or truckful. The old style was to say spoonsful or trucksful for the plural. Today it is more usual to say spoonfuls or truckfuls. Both the old style (spoonsful) and the new style (spoonfuls) are normally acceptable, but you should be consistent in your choice.
Here are some examples:
• teaspoonful — teaspoonsful — teaspoonfuls
• truckful — trucksful — truckfuls
• bucketful — bucketsful — bucketfuls
• cupful — cupsful — cupfuls
With compound nouns made of [noun + noun] the second noun takes an -s for plural. The first noun acts like an adjective and as you know, adjectives in English are invariable.
Look at these examples:
• 100 trees with apples — 100 apple trees
• 1,000 cables for telephones — 1,000 telephone cables
• 20 boxes for tools — 20 tool boxes
• 10 stops for buses — 10 bus stops
• 4,000 wheels for cars — 4,000 car wheels
Some compound nouns have no obvious base word and you may need to consult a dictionary to find the plural:
You can try the easy and fun activity below: