Prefixes (at the beginning of words) can help you to understand what a new word means. Here are some common prefixes.
un- and dis-
These prefixes have two meanings: they can have a negative meaning (as above), but they can also mean ‘the opposite of an action’ or ‘to reverse an action’. This meaning is used with certain verbs.
- I locked the door when I left, but I lost the key, so I couldn’t it unlock it when I got back.
- I had to pack my suitcase (= put everything in it) very quickly, so when I unpacked (= took everything out) at the hotel, most of my clothes looked terrible.
- The plane appeared in the sky, then suddenly disappeared behind a cloud.
- In the morning you get dressed (= put on your clothes); when you go to bed you get undressed (= take off your clothes).
re- (= again)
- My homework was terrible, so I had to redo it.
- The shop closed down but will reopen next month.
- I failed my exam but I can retake (or redo/resit) it next year.
over- (= too much)
- I think my boss is overdoing it at the moment. (= working too hard; also overwork)
- I went to bed very late and I overslept (= slept too long) this morning.
- The shop assistant overcharged me. (= asked me for too much money)
mis- (= badly or incorrectly)
- I’m afraid I misunderstood what he said.
- Two of the students misread the first question.
|inter||between, among||interstate, international|
|mega||great||mega city, megaphone|
|mono||one, single||monotheistic, monologue|
|pro||forward, supporting||progress, propel, profess|
|semi||half, partly||semidetached semiprivate|
|sub||below, under||submarine, submerge|
|ultra||beyond||ultrasound, ultra light|
|un||not, uncertain||uneducated, unbearable|