Compound Nouns

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 below). 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:

1. open or spaced - space between words (tennis shoe)
2. hyphenated - hyphen between words (six-pack)
3. closed or solid - no space or hyphen between words (bedroom)

Here are some examples of compound nouns:

noun	+	noun	bus stop	Is this the bus stop for the number 12 bus?
			fire-fly	In the tropics you can see fire-flies at night.
			football	Shall we play football today?
adjective	+	noun	full moon	I always feel crazy at full moon.
			blackboard	Clean the blackboard please.
			software	I can't install this software on my PC.
verb(-ing)	+	noun	breakfast	We always eat breakfast at 8am.
			washing machine	Put the clothes in the red washing machine.
			swimming pool	What a beautiful swimming pool!
noun	+	verb(-ing)	sunrise	I like to get up at sunrise.
			haircut	You need a haircut.
			train-spotting	His hobby is train-spotting.
verb	+	preposition	check-out	Please remember that check-out is at 12 noon.
noun	+	prepositional phrase	mother-in-law	My mother-in-law lives with us.
preposition	+	noun	underworld	Do you think the police accept money from the underworld?
noun	+	adjective	truckful	We need 10 truckfuls of bricks.

Pronunciation

Compound nouns tend to have more stress on the first word. In the phrase "pink ball", both words are equally stressed (as you know, adjectives and nouns are always stressed). In the compound noun "golf ball", the first word is stressed more (even though both words are nouns, and nouns are always stressed). Since "golf ball" is a compound noun we consider it as a single noun and so it has a single main stress - on the first word. Stress is important in compound nouns. For example, it helps us know if somebody said "a GREEN HOUSE" (a house which is painted green) or "a GREENhouse" (a building made of glass for growing plants inside).

British/American differences

Different varieties of English, and even different writers, may use the open, hyphenated or closed form for the same compound noun. It is partly a matter of style. There are no definite rules. For example we can find:

• container ship
• container-ship
• containership

If you are not sure which form to use, please check in a good dictionary.

Plural Forms of Compound Nouns

In general we make the plural of a compound noun by adding -s to the "base word" (the most "significant" word). Look at these examples:

singular	plural
a tennis shoe	three tennis shoes
one assistant headmaster	five assistant headmasters
the sergeant major	some sergeants major
a mother-in-law	two mothers-in-law
an assistant secretary of state	three assistant secretaries of state
my toothbrush	our toothbrushes
a woman-doctor	four women-doctors
a doctor of philosophy	two doctors of philosophy
a passerby, a passer-by	two passersby, two 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:

	old style plural (very formal)	new style plural
teaspoonful	3 teaspoonsful of sugar	3 teaspoonfuls of sugar
truckful	5 trucksful of sand	5 truckfuls of sand
bucketful	2 bucketsful of water	2 bucketfuls of water
cupful	4 cupsful of rice	4 cupfuls of rice

Some compound nouns have no obvious base word and you may need to consult a dictionary to find the plural:

• higher-ups
• also-rans
• go-betweens
• has-beens
• good-for-nothings
• grown-ups

Note that with compound nouns made of [noun + noun] the first noun is like an adjective and therefore does not usually take an -s. A tree that has apples has many apples, but we say an apple tree, not apples tree; matchbox not matchesbox; toothbrush not teethbrush.

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:

long plural form becomes →	plural compound noun [noun + noun]
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

https://www.englishclub.com/grammar/nouns-compound.htm