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Word formation: prefixes and suffixes
C1 C1 grammar · lesson 14 of 16
Knowing how English builds words with prefixes and suffixes lets you understand and create many new words. It is also tested in most advanced English exams.
Prefixes: changing the meaning
A prefix goes at the beginning of a word and changes its meaning, but not usually its word class.
| Prefix | Meaning | Examples |
|---|---|---|
| un-, in-, im-, il-, ir-, dis- | not / opposite | unlikely, impossible, illegal, irregular, disagree |
| mis- | wrongly | misunderstand, mislead |
| over- / under- | too much / too little | overwork, underestimate |
| re- | again | rebuild, reconsider |
| pre- / post- | before / after | preview, postwar |
| co-, inter-, out- | together / between / more than | cooperate, international, outnumber |
Suffixes: changing the word class
A suffix goes at the end of a word and usually changes its word class (noun, verb, adjective, adverb).
| Makes a… | Suffixes | Examples |
|---|---|---|
| Noun | -ness, -ity, -ment, -tion, -ance/-ence, -ship, -hood | kindness, flexibility, agreement, friendship, childhood |
| Verb | -ise/-ize, -en, -ify | modernise, widen, simplify |
| Adjective | -able/-ible, -ful, -less, -ous, -ive, -al | affordable, careless, dangerous, effective |
| Adverb | -ly, -wards | finally, backwards |
Building longer words
You can often combine several parts: help → helpful → unhelpful → unhelpfully. Pay attention to spelling changes, such as dropping a final e or changing y to i.
The instructions were unclear, so we misread them.
Ken is famous for his generosity.
The government wants to modernise the railways.
It was irresponsible to leave the gate open.
Maria’s happiness was obvious to everyone.
They have decided to widen the road.
The results were disappointing but not unexpected.
Using word class to choose the right form
In exams and in writing, look at the position of the gap to decide which word class you need. After an article or a possessive (the, a, her) you usually need a noun. Before a noun or after be, seem, become you usually need an adjective. To describe how an action is done, you need an adverb. Then think about meaning: should the word be positive or negative? A sentence like The plan was completely ___ (success) after failed needs unsuccessful, not successful.
Common mistakes
✗ It’s unpossible to finish today.
✓ It’s impossible to finish today.
✗ She showed great kindliness and happyness.
✓ She showed great kindness and happiness.
✗ He is very responsable.
✓ He is very responsible.
✗ We need to short the text.
✓ We need to shorten the text.