| polite | impolite | 
| regular | irregular | 
| literate | illiterate | 
| reversible | irreversible | 
| moral | immoral | 
| tolerable | intolerable | 
| responsible | irresponsible | 
| active | inactive | 
| 1. | semi-: 'partly' | 
| 2. | multi-: 'many (or several)' | 
| 3. | anti-: 'opposed to; opposite of; or preventing' |