A prefix is a group of letters at the beginning of a word. It indicates part of the meaning of the whole word. If you know the most common prefixes, it will help to deduce the meaning of new words. So even if you don’t know a word, if you recognise its prefix and know the meaning of the prefix, it will help you guess the meaning of the whole word.
Example: “dis” is a prefix that means “not”. It has a negative meaning.
So once you know the meaning of the “dis” prefix, you will perhaps be able to guess the meaning of the word “dislike”
Example: I dislike him = I do not like him.
Sometimes there is a hyphen ( – ) between the prefix and the rest of the word. Example: anti-war.
Be careful. Sometimes what looks like a prefix is not a prefix and the meaning is quite different. Example: “distant”
Use a good dictionary to check the meaning of all new words.
In this lesson, you will learn the most common prefixes in the English language.
The prefix “anti” means against or opposed to.
antisocial = against being social. Not liking making friends and talking to people.
She doesn’t have many friends because she is antisocial.
antibiotic = a medication that destroys bacteria
He is taking antibiotics to treat his infection.
Other examples: anti-war, anti-racism, anticlimax, anti-aircraft
The prefix “de” means reverse or change
dehydrated = not enough water in the body. (opposite of hydrated)
Mark is drinking some water because he is feeling dehydrated.
debug = to remove bugs (errors) from a computer program.
He is trying to debug the accounts software.
Other examples: derail, de-ice, decaffeinated
The prefix “dis” means not or the opposite of.
disagree = to not agree
Sarah disagrees with Clare.
dislike = to not like
Mark dislikes his sister.
Other examples: disallow, disconnect, disrespect
The prefix “hyper ” means extreme / excessive / very big / very high
hyperactive = excessively active
Paul is a hyperactive child.
hypertension = high blood pressure
David is suffering from hypertension.
Other examples: hypermarket, hypersensitive, hyperventilate
il, im, in, ir
The prefixes “il”, “im”, “in” and “ir” mean not. They have a negative meaning.
illegal = not legal
It is illegal to carry a gun.
impossible = not possible
There is too much noise. It’s impossible to sleep.
inactive = not active
The old man is very inactive.
irregular = not regular
The verb “to be” is irregular.
Other examples: illegible, impotent, insecure, irrational
The prefix “inter” means between / among.
interact = to communicate with other people
The new manager interacts very well with the rest of the team.
international = between nations
The world cup is an international event.
Other examples: interchange, internal
The prefix “mid” means middle.
midday = twelve o’ clock (middle of the day)
“It’s midday, let’s have lunch.”
midsummer = middle of summer
Midsummer is my favourite time of the year.
Other examples: midnight, midriff, midway
The prefix “mis” means bad / badly / wrong / wrongly
misbehave = to behave badly
Mark has misbehaved in school.
misspelling = a wrong spelling
Lionel Messi is a footbill player.
“footbill” is a misspelling.
Other examples: misprint, mispronounce, mistake
The prefix “non” means no / not / without
non-smoking (adjective) = A place where people are NOT allowed to smoke.
The train is non-smoking.
nonsense = without sense / no sense
“I don’t agree. You are talking nonsense!”
Other examples: nonfiction, non-payment
The prefix “over” means too much / an excessive amount
overcook = to cook too much
The meat is overcooked.
overexcited = too excited
The children are overexcited.
Other examples: overcharge, overconfident, overrated
The prefix “post” means after / behind / later
postpone = to delay something until later.
I have postponed the meeting to the 26th December.
post-war = after the war
The post-war period was a very difficult time for everybody.
Other examples: postdate, post-election
The prefix “pre” means before / earlier.
pre-dinner = before dinner
Michael is having a pre-dinner drink.
predict = to say that something will happen in the future (we say it BEFORE it happens)
The director predicts that sales will increase.
Other examples: prefix, prehistoric, prepare
The prefix “pro” means in support of / favouring
pro-independence = in support of independence
John took part in a Scottish pro-independence march.
pro-peace = in support of peace
Jane is pro-peace.
Other examples: pro-choice, pro-democracy
The prefix “re ” means to do something again.
rewrite = to write something again
I made a mistake so I am rewriting a cheque.
reheat = to heat something again
The coffee is cold so I am reheating it.
Other examples: redo, review, revise
The prefix “sub” means under / below
submarine = a ship that travels underwater
The Royal Navy has several submarines.
subway = an underground passage to allow people to cross a busy road. (British English)
subway = an underground train. (America)
She takes the New York subway to go to work every day.
Other examples: submerge, substandard
The prefix “un” means not / against / opposite
unplug= to remove a plug from the socket (opposite of “to plug in”)
He always unplugs the television during a storm.
unhappy= not happy
Laura is unhappy because she cannot find a job.
Other examples: unlock, unpack, unsure
The prefix “under” means not enough / below.
undercook = to cook something (but not enough)
The meat is undercooked.
underage = below the legal age.
There is a law against underage drinking.
Other examples: underestimate, underdeveloped