Formation
A compound noun is a noun that is made up of two or more words.
These are very common, and new combinations are invented almost daily. They normally have two parts.
The first part tells us what kind of object or person it is, or what its purpose is (police, boy, water, dining, bed).
The second part identifies the object or person in question (man, friend, tank, table, room).
| What type / what purpose |
What or who |
| police |
man |
| boy |
friend |
| water |
tank |
| dining |
table |
| bed |
room |
The two parts may be written in a number of ways :
1. as one word.
Examples: policeman, boyfriend
2. as two words joined with a hyphen.
Examples: dining-table
3. as two separate words.
Examples: fish tank.
There are no clear rules about this - so write the common compounds that you know well as one word, and the others as two words.
| The two parts may be: |
Examples |
| noun + noun |
bedroom
water tank
motorcycle
printer cartridge |
| noun + verb |
rainfall
haircut
train-spotting |
| noun + adverb |
hanger-on
passer-by |
| verb + noun |
washing machine
driving licence
swimming pool |
| verb + adverb* |
lookout
take-off
drawback |
| adjective + noun |
greenhouse
software
redhead |
| adjective + verb |
dry-cleaning
public speaking |
| adverb + noun |
onlooker
bystander |
| adverb + verb* |
output
overthrow
upturn
input |
Compound nouns often have a meaning that is different from the two separate words.
Pronunciation
Compound nouns tend to have more stress on the first word.
Stress is important in pronunciation, as it distinguishes between a compound noun (e.g. greenhouse) and an adjective with a noun (e.g. green house).
In compound nouns, the stress usually falls on the first syllable:
- a 'greenhouse = place where we grow plants (compound noun)
- a green 'house = house painted green (adjective and noun)
- a 'bluebird = type of bird (compound noun)
- a blue 'bird = any bird with blue feathers (adjective and noun)
*Many common compound nouns are formed from phrasal verbs (verb + adverb or adverb + verb).
Examples
breakdown, outbreak, outcome, cutback, drive-in, drop-out, feedback, flyover, hold-up, hangover, outlay, outlet, inlet, makeup, output, set-back, stand-in, takeaway, walkover.
Plural
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
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 |