English Vocabulary in Use Upper-intermediate » Unit 71: Prefixes
Prefixes are often used to give adjectives a negative or an opposite meaning. For example, fair/unfair, experienced/inexperienced and similar/dissimilar are opposites. Other examples are 'unnatural', 'inedible', 'disorganised'. Unfortunately, there is no easy way of knowing which prefix any adjective will use to form its opposite.
in- becomes im- before a root beginning with 'm' or 'p', e.g. immature, impatient, immoral, impossible, improbable. Similarly in- becomes ir- before a word beginning with 'r', e.g. irregular, irresponsible, irreplaceable, and il- before a word beginning with 'l', e.g. illegal, illegible, illiterate.
The prefix in- (and its variations) does not always have a negative meaning - often it gives the idea of inside or into, e.g. internal, import, insert, income.
The prefixes un- and dis- can also form the opposites of verbs, e.g. tie/untie, appear/disappear.
These prefixes are used to reverse the action of the verb. Here are some more examples: disagree, disapprove, disbelieve, disconnect, discourage, dislike, disprove, disqualify, unbend, undo, undress, unfold, unload, unlock, unveil, unwrap, unzip.
Some words with prefixes use a hyphen. Check in a dictionary if you're not sure.
| prefix | meaning | examples |
| anti | against | anti-war antisocial antibiotic antiseptic |
| auto | of or by oneself | autograph auto-pilot autobiography |
| bi | two/twice | bicycle bilateral biannual bilingual |
| ex | former | ex-wife ex-smoker ex-boss |
| ex | out of | extract exhale excommunicate |
| micro | small | microbiology microchip microscopic microwave |
| mis | badly/wrongly | misunderstand mistranslate mislead |
| mono | one/single | monolingual monologue monogamous |
| multi | many | multinational multimedia multi-purpose |
| over | too much | overdo overtired oversleep overeat |
| post | after | post-war postgraduate post-impressionist |
| pre | before | preconceived pre-war pre-judge |
| pro | in favour of | pro-government pro-revolutionary |
| pseudo | false | pseudo-scientific pseudo-intellectual |
| re | again/back | rewrite regain rearrange repay replace renew |
| semi | half | semi-circular semi-final semi-detached |
| sub | under | subway submarine subdivision |
| under | not enough | underworked underused undercooked |
The words you need to communicate with confidence. Vocabulary explanations and practice for elementary level (A2) learners of English. Perfect for both self-study and classroom activities. Quickly expand your vocabulary with 60 units of easy to understand explanations and practice exercises.
The words you need to communicate with confidence. Vocabulary explanations and practice for pre-intermediate and intermediate level (B1) learners of English. Perfect for both self-study and classroom activities. Quickly expand your vocabulary with 100 units of easy to understand explanations and practice exercises.
The words you need to communicate with confidence. Vocabulary explanations and practice for advanced level (C1 to C2) learners of English. Perfect for both self-study and classroom activities. Quickly expand your vocabulary with over 100 units of easy to understand explanations and practice exercises.