Page 57 - English Vocabulary in Use : Elementary

25 Prefixes

Prefixes (at the beginning of words) can help you to understand what a new word means.
Here are some common prefixes.

prefix meaning examples
ex (+noun) was but not now ex-wife, ex-president

half (+noun or adjective) 50% of something half-price, half- hour
in, im (+adjective) not | informal, impossible

non (+adjective or noun) not non-smoking
pre before pre-school

re (+verb) again redo, rewrite
un (+adjective or noun) not unhappy, unsafe |

An ex-wife is a wife who is now divorced.
President Gorbachev is an ex-President of Russia.
A half-hour journey is a journey of 30 minutes.
Something that cost £10 yesterday and costs £5 today is half-price.
Informal clothes are clothes like jeans and trainers. Formal clothes are things like a suit.
If something is impossible, you can’t do it. It is impossible to read with your eyes closed.
A non-smoking room is a room where people may not smoke,
Pre-school children are children who are still too young to go to school.
To redo something is to do it a second time and to rewrite something is to write it a second
time.
Unhappy means sad, the opposite of happy.
Unsafe means dangerous, the opposite of safe.

Tip: Sometimes words with prefixes have a hyphen (-), e.g. a half-hour programme, and
sometimes they don’t, e.g. an impossible question. Use a dictionary when you are not sure
if there is a hyphen or not.

54 English Vocabulary in Use (elementary)