A prefix is a letter or group of letters added to the beginning of a word to make a new word. Negative prefixes create a new word with an opposite or negative meaning. Sometimes adding a prefix to a word to make it negative isn’t as simple as it seems. There are no definite rules about which prefix can be used to form a negative adjective.

Level B1/B2

Negative Prefixes

Un- is the most common negative prefix meaning “not”. It’s used to give opposite and negative meanings to adjectives, adverbs and nouns. The un- prefix tends to be used with verbs, words formed from verbs, and adjectives describing feelings or judgments. Words with un- may begin with a vowel or a consonant.

  • happy – unhappy
  • acceptable – unacceptable
  • certain – uncertain
  • fair – unfair
  • likely – unlikely
  • lucky – unlucky
  • realistic – unrealistic
  • surprising – unsurprsing
  • tidy – untidy
  • wanted – unwanted
  • able – unable
  • fit – unfit
  • believable – unbelievable
  • caring – uncaring
  • pleasant – unpleasant
  • fortunate – unfortunate
  • safe – unsafe
  • comfortable – uncomfortable
  • interested – uninterested
  • limited – unlimited
  • selfish – unselfish

The prefix in– is the second most common negative prefix. In- changes its form to il- before an l; to im- before b, m or p; and to ir- before r.

in- 

  • dependent – independent
  • visible – invisible
  • appropriate – inappropriate
  • expensive – inexpensive
  • accurate – inaccurate
  • complete – incomplete
  • correct – incorrect
  • effective – ineffective
  • formal – informal
  • valid – invalid
  • competent – incompetent
  • decisive – indecisive
  • direct – indirect
  • cosiderate – inconsiderate

il- is used with adjectives beginning with l

  • legal – illegal
  • legible – illegible
  • literate – illiterate
  • logical – illogical

im- is used with adjectives beginning with b, m, p

  • patient – impatient
  • polite – impolite
  • perfect – imperfect
  • moral – immoral
  • mature – immature
  • possible – impossible
  • movable – immovable
  • practical – impractical
  • mortal – immortal
  • probable – improbable

ir- is used with adjectives beginning with r

  • responsible – irresponsible
  • regular – irregular
  • relevant – irrelevant
  • rational – irrational
  • resistable – irresistable
  • removable – irremovable
  • respective – irrespective
  • replaceable – irreplaceable

Prefix dis- changes the meaning of the word to “not something” or “the opposite of something”

  • honest – dishonest
  • organized – disorganized
  • courteous – discourteous
  • interested – disinterested
  • comfort – discomfort
  • appear – disappear
  • advantage – disadvantage
  • agree – disagree
  • satisfied – dissatisfied
  • like – dislike
  • loyal – disloyal

Have practice using negative prefixes.

Task 1. Write the negative form of these words by adding a negative prefix: “un-“, “dis-“, “ir-“, “il-“, “in-“, or “im-“.

  1. ____comfortable
  2. ____patient
  3. ____honest
  4. ____ lucky
  5. ____formal
  6. ____possible
  7. ____popular
  8. ____lock
  9. ____appear
  10. ____agree
  11. ____legal
  12. ____polite
  13. ____like
  14. ____logical
  15. ____convenient
  16. ____frequent
  17. ____believable
  18. ____relevant
  19. ____mature
  20. ____approve
  21. ____dependent
  22. ____legible
  23. ____curable
  24. ____responsible
  25. ____moral
  26. ____familiar
  27. ____accurate
  28. ____regular
  29. ____grateful
  30. ____resistible

Task 2.Use the negative prefixes and the adjectives given to complete the sentences.

possible      honest      sociable      patient      legal      responsible     pleasant      polite

  1. My aunt’s children are so __________. They never say please and thank you.
  2. Tim’s really __________. He never tells the truth.
  3. I wish I wasn’t so __________, but I really don’t like going out or talking to new people.
  4. Don’t be so __________. I’ll be ready in 5 minutes.
  5. Liz can be really __________ sometimes. She seems like upsetting people.
  6. This maths problem is __________. I can’t to it.
  7. I wouldn’t ask Jack to look after my little brother. He’s too __________.
  8. In Britain, it’s __________ to drive under the age of 17.

Task 3. Complete the sentences by adding the correct prefix for each word.

  1. It’s rather ___polite if you don’t say ‘please’ a lot in English.
  2. My parents are extremely generous with their time and money. They are very ___selfish.
  3. If the traffic is bad, it’ll be ___possible to get to the match on time.
  4. It’s ___legal to drive along that street; it’s for pedestrians only.
  5. My mum thought a burglar had been in my bedroom, but it’s always really ___tidy.
  6. It was completely ___responsible of you to go away for the weekend without telling us.
  7. Mike’s pretty ___happy about going on holiday with his girlfriend’s parents.
  8. I never know when to expect the post. It’s so ___regular.
  9. Taking a large suitcase on a walking holiday is a bit ___practical.

Task 4. Fill in negative prefixes to form the OPPOSITE of each of the adjectives below. In some cases, more than one prefix is possible.

___acceptable     ___accurate     ___adequate     ___agreeable     ___approachable    ___appropriate     ___bearable     ___compatible ___complete     ___conscious    ___contented     ___convenient     ___credible     ___decisive     ___desirable    ___discreet   ___excusable   ___experienced     ___faithful     ___flexible    ___frequent     ___grateful     ___healthy     ___helpful     ___hospitable  ___legal     ___legible   ___legitimate     ___literate     ___logical    ___mature     ___moral     ___mortal     ___obedient   ___organised    ___passive     ___patient    ___perfect     ___personal     ___polite    ___probable     ___readable     ___regular   ___resolute     ___responsible    ___respectful     ___sane     ___satisfactory     ___satisfied     ___sociable    ___sufficient   ___variable     ___visible     ___willing