Word formation: prefixes and suffixes
Unhappy, impossible, dislike; teacher, decision, payment, kindness; useful, careless, enjoyable, and adverbs with -ly.
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English builds many words from a word you already know. A prefix goes at the start and changes the meaning: happy → unhappy. A suffix goes at the end and usually changes the kind of word: teach (verb) → teacher (noun), care (noun) → careful (adjective). If you know the common prefixes and suffixes, you can understand new words and build the right form in a sentence.
Negative prefixes: un-, in-, im-, dis-
These prefixes mean "not" or "the opposite of".
Prefix | Examples |
|---|---|
un- | unhappy, unusual, unfriendly, unable, unlucky |
in- | incorrect, independent, informal, invisible |
im- (before p, m) | impossible, impatient, immature |
il- (before l) | illegal |
ir- (before r) | irregular |
dis- | dislike, disagree, dishonest, disappear |
Un- is the most common. There is no rule that tells you which prefix a word takes, so learn the word with its prefix. The spelling rule for im-, il- and ir- only applies to words that take in-: unpopular and unlucky keep un-.
- I'm sorry, that answer is incorrect.
- It's impossible to park in the city centre.
- I disagree with you.
- Incorrect: It's unpossible to finish this today.
- Correct: It's impossible to finish this today.Possible takes in-, and before p it becomes im-.
Nouns for people: -er, -or, -ist
Add -er or -or to a verb, or -ist to a noun, for the person who does it.
- teach → teacher, drive → driver, play → player
- act → actor, visit → visitor
- art → artist, science → scientist
Nouns for things and ideas: -tion, -ment, -ness
Suffix | Made from | Examples |
|---|---|---|
-tion, -sion | a verb | educate → education, decide → decision |
-ment | a verb | pay → payment, improve → improvement, agree → agreement |
-ness | an adjective | kind → kindness, happy → happiness, ill → illness |
Watch the spelling: a final -e often goes (educate → education), and -y after a consonant becomes -i- (happy → happiness).
- Thank you for your kindness.
- We need to make a decision today.
- Incorrect: We need to make a decide today.
- Correct: We need to make a decision today.After a, you need the noun: decision.
Adjectives: -ful, -less, -able
Suffix | Meaning | Examples |
|---|---|---|
-ful | with, full of | useful, careful, helpful, beautiful |
-less | without | useless, careless, homeless, hopeless |
-able | can be done | enjoyable, washable, reliable, acceptable |
-ful is spelt with one l: beautiful, careful. Not every -ful word has a -less partner: there is beautiful, but no beautiless.
- My old laptop is useless. It doesn't even switch on.
- We had a really enjoyable evening.
- Incorrect: It's a beautifull day.
- Correct: It's a beautiful day.The suffix -ful has one l.
- Incorrect: This app is really useless. I use it every day to plan my week.
- Correct: This app is really useful. I use it every day to plan my week.Useful means it helps you. Useless means it doesn't work or doesn't help.
Adverbs: -ly
Most adverbs of manner are an adjective + -ly, as at A2: careful → carefully, quick → quickly. Watch the spelling: easy → easily, happy → happily, gentle → gently, basic → basically.
A few words that end in -ly are adjectives, not adverbs: friendly, lovely, lonely, ugly. They have no common adverb form, so use a phrase: She smiled at me in a friendly way.
Use the right kind of word
In a sentence, first decide what kind of word the gap needs, then choose the ending.
- After a, the, my or an adjective: a noun (a good decision).
- After be, look, seem or before a noun: an adjective (It looks comfortable.)
- To describe an action: an adverb (Drive carefully.)