Prefixes in English: Meaning, Examples and Word Formation Guide

Have you ever seen a word like unhappy, rewrite, impossible or misunderstand and guessed its meaning before checking a dictionary? That is the power of prefixes in English.

A prefix is a small group of letters added to the beginning of a word to change its meaning.

For example:

• happy → unhappy
• write → rewrite
• possible → impossible
• understand → misunderstand

Learning prefixes in English helps you understand new vocabulary faster, improve your reading skills and perform better in word formation tasks in exams such as B2 First and C1 Advanced.

What is a Prefix?

A prefix is added to the beginning of a base word.

The base word is the main word.

For example:

un-	happy	unhappy
re-	write	rewrite
mis-	understand	misunderstand
pre-	school	preschool
over-	cooked	overcooked

A prefix usually changes the meaning of the word, but it does not always change the word class.

For example:

• happy = adjective
• unhappy = adjective

The word is still an adjective, but the meaning has changed.

Why are Prefixes Important?

Prefixes are useful because they help you:

• understand unfamiliar words
• build your vocabulary faster
• guess meanings from context
• improve your spelling
• prepare for word formation exercises
• write and speak more precisely

For example, if you know that mis- often means “wrongly” or “badly”, you can understand words such as:

• misunderstand
• misbehave
• mislead
• mispronounce
• misuse

A good learner does not learn words one by one only. A good learner notices patterns. Prefixes are one of the most useful patterns in English vocabulary.

Common Prefixes in English

1. Negative Prefixes in English

Negative prefixes make a word negative or opposite in meaning.

Un-

Un- is one of the most common prefixes in English. It often means not or the opposite of.

Examples:

unhappy	not happy
unfair	not fair
unclear	not clear
unlucky	not lucky
unusual	not usual
uncomfortable	not comfortable

Example sentences:

• The instructions were unclear, so nobody knew what to do.
• She felt uncomfortable during the interview.
• It was unfair to blame him for the mistake.
• We had an unusual amount of rain this spring.

In-, Im-, Il-, Ir-

These prefixes also mean not, but the form depends on the first letter of the base word.

in-	many words	incorrect, inactive, invisible
im-	often before p, b, m	impossible, impatient, immature
il-	before l	illegal, illogical
ir-	before r	irregular, irresponsible

Examples:

• Your answer is incorrect.
• It is impossible to finish this in five minutes.
• Parking here is illegal.
• His behaviour was completely irresponsible.

Be careful: we do not usually choose these prefixes freely. You need to learn which prefix goes with which word.

For example:

• possible → impossible
• legal → illegal
• regular → irregular
• correct → incorrect

Not:

• unpossible
• inlegal
• unregular

Dis-

Dis- can mean not, opposite of, or reverse an action.

Examples:

disagree	not agree
disappear	stop being visible
dislike	not like
dishonest	not honest
disconnect	separate or break a connection

Example sentences:

• I disagree with your opinion, but I respect it.
• The sun disappeared behind the clouds.
• It was dishonest of him to hide the truth.
• Please disconnect the device before cleaning it.

Non-

Non- means not or without. It is often used in more formal or technical English.

Examples:

non-smoker	someone who does not smoke
non-fiction	writing based on facts
non-verbal	not using words
non-profit	not created mainly to make money
non-stop	without stopping

Example sentences:

• This is a non-smoking area.
• She prefers non-fiction books.
• Body language is a form of non-verbal communication.
• The organisation is non-profit.

2. Prefixes That Show Repetition

Re-

Re- means again or back.

Examples:

rewrite	write again
reread	read again
rebuild	build again
return	come/go back
review	look at again
reconnect	connect again

Example sentences:

• You should reread the text before answering the questions.
• I need to rewrite this paragraph because it is unclear.
• They decided to rebuild the old theatre.
• Let’s review the main points before the test.

This prefix is extremely useful for students because many study verbs use re-:

• revise
• review
• rewrite
• reread
• redo
• reconsider

3. Prefixes That Show Something Is Wrong

Mis-

Mis- means wrongly, badly or incorrectly.

Examples:

misunderstand	understand wrongly
mispronounce	pronounce wrongly
misspell	spell wrongly
misbehave	behave badly
misuse	use incorrectly
mislead	give someone the wrong idea

Example sentences:

• I think you misunderstood my question.
• Many learners mispronounce this word.
• Be careful not to misspell his name.
• The advert was criticised because it could mislead customers.

A very useful learner sentence:

• Sorry, I think I misunderstood what you meant.

4. Prefixes That Show Time

Pre-

Pre- means before.

Examples:

preview	see before
preheat	heat before cooking
prepay	pay before
preschool	before school age
pre-war	before the war
pre-exam	before an exam

Example sentences:

• Please preheat the oven to 180°C.
• We watched a preview of the new film.
• The teacher gave us some pre-exam advice.
• This building dates from the pre-war period.

Post-

Post- means after.

Examples:

post-war	after the war
postgraduate	after a first university degree
post-exam	after an exam
postnatal	after birth
postscript	something added after the main text

Example sentences:

• He is doing a postgraduate course in London.
• The country changed greatly in the post-war years.
• We had a post-exam discussion about the difficult questions.

5. Prefixes That Show Amount or Degree

Over-

Over- can mean too much.

Examples:

overcook	cook too much
overwork	work too much
overthink	think too much
overcrowded	too crowded
overpriced	too expensive
overconfident	too confident

Example sentences:

• Don’t overcook the vegetables.
• She became ill because she was overworked.
• The hotel was overpriced for what it offered.
• Try not to overthink every small mistake.

Under-

Under- can mean not enough or below.

Examples:

undercook	not cook enough
underestimate	think something is less important than it is
underpaid	not paid enough
underground	below the ground
underdeveloped	not fully developed

Example sentences:

• The chicken was undercooked, so we couldn’t eat it.
• Don’t underestimate how difficult the exam can be.
• Many workers feel underpaid.
• The city has an excellent underground system.

Super-

Super- means very, above, or more than usual.

Examples:

supermarket	a large shop
superhuman	more than human
superpower	a very powerful country or ability
superfast	very fast
supernatural	beyond natural explanation

Example sentences:

• The train is superfast.
• The story includes supernatural events.
• Some people seem to have superhuman energy.

In informal English, super is also used as an intensifier:

• The lesson was super useful.
• She was super friendly.

This is common in conversation, but in formal writing, use very, extremely or highly instead.

6. Prefixes That Show Position or Direction

Sub-

Sub- often means under or below.

Examples:

submarine	a vessel that travels under water
subway	an underground passage or railway
subtitle	words shown below a video
subconscious	below the level of conscious thought
substandard	below the expected standard

Example sentences:

• I watched the film with English subtitles.
• The accommodation was substandard.
• A submarine travels below the surface of the sea.

Inter-

Inter- means between or among.

Examples:

international	between countries
interact	communicate with each other
intercity	between cities
interconnected	connected with each other
interview	a formal meeting between people

Example sentences:

• English is an international language.
• Students should interact more in class.
• These problems are interconnected.
• She has an interview next week.

Trans-

Trans- often means across, through or change.

Examples:

transport	carry across/from one place to another
transfer	move from one place to another
translate	change from one language to another
transform	change completely
transatlantic	across the Atlantic

Example sentences:

• Can you translate this sentence into English?
• The project completely transformed the town.
• He was transferred to another department.

7. Prefixes That Show Number

Mono-

Mono- means one.

Examples:

• monolingual
• monopoly
• monologue
• monoculture

Example sentences:

• A monolingual dictionary explains words in one language.
• The actor performed a powerful monologue.

Bi-

Bi- means two.

Examples:

• bilingual
• bicycle
• bilateral
• biannual

Example sentences:

• She is bilingual in English and Spanish.
• A bicycle has two wheels.

Be careful with biannual. It can sometimes mean twice a year or once every two years, so it is often clearer to say exactly what you mean.

Tri-

Tri- means three.

Examples:

• triangle
• trilingual
• trilogy
• tripod

Example sentences:

• A triangle has three sides.
• He is trilingual; he speaks Serbian, English and German.

Multi-

Multi- means many.

Examples:

• multicultural
• multilingual
• multinational
• multipurpose
• multimedia

Example sentences:

• London is a multicultural city.
• She works for a multinational company.
• This is a multipurpose tool.

8. Prefixes with People, Society and Communication

Co-

Co- means together or with.

Examples:

cooperate	work together
co-worker	someone you work with
co-author	someone who writes something with another person
coexist	exist together
co-pilot	a second pilot

Example sentences:

• The two schools decided to cooperate.
• She wrote the article with a co-author.
• Good co-workers make work much more pleasant.

Anti-

Anti- means against.

Examples:

anti-war	against war
antibacterial	against bacteria
anti-social	against normal social behaviour
anti-government	against the government
antivirus	against computer viruses

Example sentences:

• This cream is antibacterial.
• The protest was mainly anti-war.
• The computer needs antivirus software.

Pro-

Pro- means in favour of.

Examples:

pro-European	in favour of Europe/the EU
pro-democracy	in favour of democracy
pro-environment	in favour of protecting the environment
pro-choice	in favour of choice

Example sentences:

• The article takes a pro-environment position.
• The campaign is strongly pro-democracy.

Prefixes and Hyphens

Some prefixes are written together with the base word:

• unhappy
• impossible
• rewrite
• misunderstand

Some are often written with a hyphen, especially when the word might look confusing or when the base word begins with a capital letter.

Examples:

• anti-war
• non-smoking
• pre-exam
• post-war
• co-worker
• ex-president

There are no perfect rules for every word, so it is always wise to check a reliable dictionary if you are unsure. English spelling likes to keep us humble — a noble tradition, though not always a convenient one.

Common Mistakes with Prefixes in English

Mistake 1: Using the Wrong Negative Prefix

Incorrect:

• This answer is uncorrect.
• It is unpossible.
• His behaviour was unresponsible.

Correct:

• This answer is incorrect.
• It is impossible.
• His behaviour was irresponsible.

Some words take un-, some take in-, im-, il- or ir-. You need to learn the common combinations.

Mistake 2: Confusing Mis- and Dis-

Mis- usually means wrongly.

• misunderstand = understand wrongly
• mispronounce = pronounce wrongly

Dis- often means the opposite or reverse.

• disagree = not agree
• disappear = stop being visible
• disconnect = break a connection

Compare:

• I misunderstood the instructions.
  = I understood them wrongly.
• I disagreed with the instructions.
  = I did not agree with them.

Mistake 3: Forgetting That Prefixes Change Meaning

Do not add prefixes randomly. A prefix changes the meaning of the word.

Compare:

• use = do something with something
• reuse = use again
• misuse = use wrongly
• overuse = use too much

Example:

• Plastic bags are often overused.
• This word is sometimes misused by learners.
• You can reuse this bottle.

Prefixes in English for Cambridge Exams

Prefixes are especially useful for word formation tasks in Cambridge exams.

You may be given a word and need to create the correct form.

Example:

The answer was completely ________.

CORRECT

Correct answer:

The answer was completely incorrect.

Another example:

I’m afraid there has been a serious ________.

UNDERSTAND

Correct answer:

I’m afraid there has been a serious misunderstanding.

Notice that sometimes you need both a prefix and a suffix:

• understand → misunderstanding
• responsible → irresponsibility
• possible → impossibility
• legal → illegal
• honest → dishonesty

This is why word formation is not just about memorising words. You need to understand how words are built.

Useful Prefix List for Learners

un-	not/opposite	unhappy, unfair, unclear
in-	not	incorrect, inactive, invisible
im-	not	impossible, impatient, immature
il-	not	illegal, illogical
ir-	not	irregular, irresponsible
dis-	not/opposite/reverse	disagree, disappear, disconnect
non-	not/without	non-smoker, non-fiction, non-verbal
re-	again/back	rewrite, reread, return
mis-	wrongly/badly	misunderstand, mispronounce, misuse
pre-	before	preheat, preview, preschool
post-	after	post-war, postgraduate
over-	too much	overcook, overwork, overpriced
under-	not enough/below	undercook, underestimate, underpaid
inter-	between	international, interact, intercity
sub-	under/below	submarine, subtitles, substandard
trans-	across/change	transport, translate, transform
co-	together/with	cooperate, co-worker, co-author
anti-	against	anti-war, antibacterial, antivirus
pro-	in favour of	pro-environment, pro-democracy
multi-	many	multicultural, multilingual, multinational

Final Thoughts

Prefixes in English are small, but they do a big job. They can make words negative, show repetition, express time, indicate amount, or change the meaning completely.

If you learn common prefixes such as un-, re-, mis-, pre-, over-, under-, dis- and non-, you will understand many new words more easily.

The best way to learn prefixes is not to memorise long lists mechanically. Instead, notice them in real words, write your own examples and pay attention to how they are used in context.

English vocabulary is like a family tree. Once you understand the roots, prefixes and suffixes, you stop seeing words as strangers and start recognising their relatives.

Download the Prefixes in English Practice Worksheet in PDF here

You may also find these grammar lessons useful:

Suffixes in English 

Negative Prefixes and Suffixes in English 

Word Formation for B2 First 

Adjective Suffixes in English 

12 Tips to Build Your Vocabulary 

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