| A | B |
| legible | able to be read |
| illegible | not able to be read |
| legal | allowed by law |
| illegal | not allowed by law |
| responsible | trusted to do what is right |
| irresponsible | not trusted to do what is right |
| replaceable | capable of being duplicated or exchanged for another item |
| irreplaceable | not capable of being duplicated or exchanged for another item |
| regular | normal or usual |
| irregular | not normal or usual |
| section | part of a larger thing |
| intersection | the place where parts come together |
| national | related to a country |
| international | between or among countries |
| personal | related to one person |
| interpersonal | having to do with relationships between people |
| action | something that is done |
| interaction | something that's done between or among people |
| intercede | to try to help settle an argument between people |
| intercept | to take something while its between its starting point and destination |