Negative prefixes

A prefix is a group of letters (affixes) added in front of a word or a root of the word to change its meaning. A negative prefix is a prefix which carries a negative meaning 'not' , 'opposite of'.

Negative statements are the opposite of affirmative statements. In English, one way to make negative statements is by adding negative prefixes to nouns, adjectives, and verbs. Here are some English negative prefixes: a-, dis-, il-, im-, in-, ir-, non-, un-.
For example, the prefix un- can be attached to the adjective happy to create the negative adjective unhappy. Or you can use the negative adverb not. Note that there is no difference in meaning between these two forms.

Un- Prefix

This prefix is normally attached to an adjective or a noun to form an adjective or a noun.
 
affirmative negative
negative prefix not
Tom is happy. Tom is unhappy. Tom is not happy.


It is important to distinguish the negative prefix un- 'not' from the prefix un- 'do the reverse of' which is normally attached to a verb. The resulting word remains a verb.

Words

Meaning

Undo (V.)

To cancel the effect of something

Undress (V.)

To remove one's clothes

Unroll (V.)

To open something that is rolled up

Untie (V.)

To remove somebody or something that is tied

Unwrap (V.)

To undo the covering that wraps something

 

a- prefix

Words that take a- as a negative prefix is used before words beginning with consonant.
Affirmative Negative
political apolitical
sexual asexual
theist atheist

dis- prefix

Words that take dis- as a negative prefix may begin with a vowel or a consonant.
affirmative negative
agree disagree  
comfort discomfort  
mount dismount  
orient disorient  

il- prefix

Words that take il- as a negative prefix always begin with the letter l.
 
affirmative negative
legal illegal
legible illegible
literate illiterate
logical illogical
 

im- prefix

Words that take im- as a negative prefix always begin with the letter m or p.
 
affirmative negative
mobile immobile
moral immoral
perfect imperfect
possible impossible
 

in- prefix

Words that take in- as a negative prefix can begin with a vowel (except i or u) or a consonant.

 

affirmative negative
accurate inaccurate
eligible ineligible
organic inorganic
decent indecent
sane insane

Note: There are many words that begin with in- that are not words with a negative prefix. For example:
 
word does not mean
incline not cline
indulge not dulge
insist not sist
invoke not voke
 

ir- prefix

Words that take ir- as a negative prefix always begin with the letter r.

 

affirmative negative
rational irrational
reconcilable irreconcilable
regular irregular
resistible irresistible

non- prefix


Words that take non- as a negative prefix may begin with a vowel or a consonant.

 

affirmative negative
conformist nonconformist
essential nonessential
fiction nonfiction
sense nonsense

un- prefix

Words that take un- as a negative prefix may begin with a vowel or consonant.

 

affirmative negative
able unable
interesting uninteresting
usual unusual
comfortable uncomfortable
helpful unhelpful
prepared unprepared

Remember, not all words that appear to have a negative prefix are negative.

 

word does not mean
alike not like
discuss not cuss
universe not iverse
illuminate not luminate
important not portant
involve not volve
irrigate not rigate
 
Most compounds with non- are written with a hyphen in British English, but not in American English: non-alcoholic , nonalcoholic .

It is also important to distinguish the meaning of the prefix im- or in- 'not' from those carrying the meaning 'in, into' which forms a verb.

Prefiixes + initial consonant of the attached root

Words

Meaning

im + p

import (V.)

To bring goods from a foreign country

in + other consonants

inflame (V.)

To cause strong feelings, especially among a lot of people

in + other consonants

incorporate (V)

To make something part of the whole

in + other consonants

inject (V.)

To put in at speed a drug or other substance into somebody or something

in + other consonants

inhale (V.)

To breathe in

in + other consonants

intend (V.)

To have a particular plan in mind