Question

Please tell, how to distinguish and use negative prefixes in, im, il, ir, un, dis, et. for different cases? Thanks in advance.

Answer 1

affirmative negative

political  apolitical

sexual asexual

theist atheist

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

Words that take il- as a negative prefix always begin with the letter l.

affirmative negative

legal illegal

legible illegible

literate illiterate

logical illogical

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

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

decentin decentsaneinsane

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 sistin

voke not voke

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

affirmative negative

rational irrational

reconcilable irreconcilable

regular irregularre

sistible irresistible

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

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

 

Answer 2

Thanks, there are some typos: resistible irresistible

sane insane

 

Answer 3

I gained access to this list at THIRUMAVALAVAN's blog.  Very good rules on negative prefixes from Agnes Sonik below..

Answer 4

whats for preparation???is it unpreparation or impreparation???

Answer 5

You want to add the prefix to an adjective. The '-tion' in your word indicates it is a noun. The adjective form is prepared. The correct negative prefix meaning "not prepared" is unprepared.