Words can be combined to form compound nouns. These are very common, and new combinations are invented almost daily. They normally have two parts. The second part identifies the object or person in question (man, friend, tank, table, room). The first part tells us what kind of object or person it is, or what its purpose is (police, boy, water, dining, bed):
| 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.
Example: policeman, boyfriend
2. as two words joined with a hyphen.
Example: dining-table
3. as two separate words.
Example: 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.
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).
