| A | B |
| incorrigible | too firmly fixed to be reformed or changed |
| indefatigable | tireless |
| indigent (adjective) | poverty-stricken |
| indigent (noun) | someone who is poor or impoverished |
| ingratiate | to make onself acceptable |
| innocuous | harmless |
| inscrutable | so mysterious it cannot be understood |
| insipid | lacking interest or spirit; boring |
| insurgent (noun) | one who rises in revolt |
| insurgent (adjective) | describing the people who revolt |
| intemperate | lacking in self-control |
| intractable | hard to manage; not easily treated |