General Opposites:
* a-, an-: Used before words beginning with a vowel sound. Examples: amoral, anarchy, atypical.
* anti-: Against, opposed to. Examples: anti-social, antibiotic, antifreeze.
* counter-: Opposite, contrary. Examples: counter-productive, counter-argument, counter-clockwise.
* dis-: The opposite of, not. Examples: dishonest, disappear, disapprove.
* in-: Not, the opposite of. Examples: incapable, incomplete, inaccurate.
* im-: Used before words beginning with "m" or "p". Examples: impossible, immoral, impatient.
* ir-: Used before words beginning with "r". Examples: irregular, irresponsible, irrational.
* il-: Used before words beginning with "l". Examples: illegal, illiterate, illogical.
* non-: Not, the opposite of. Examples: non-fiction, non-profit, non-toxic.
* un-: The opposite of, not. Examples: unhappy, unlock, unable.
Specific Opposites:
* de-: Removal or reversal of. Examples: defrost, deactivate, declassify.
* mal-: Bad, ill, wrong. Examples: malfunction, malnourished, malpractice.
* mis-: Wrong, badly, incorrectly. Examples: misinterpret, miscalculate, misbehave.
Important Note:
It's important to remember that not all words with these prefixes will be direct opposites. Sometimes they have more nuanced meanings related to negation or opposition.