| Term | Definition |
| indefatigable | incapable of being tired out |
| indelible | incapable of being erased |
| indemnify | to insure; to repay |
| indicative | signifying; implying |
| indict | to charge with a crime; to accuse of a wrong-doing |
| indigenous | native to a particular area; inborn |
| indigent | extremely poor |
| indignant | angry as a result of unjust treatment |
| indisputable | unquestionable; without doubt |
| indissoluble | permanent |
| indoctrinate | to teach someone principles or beliefs |
| indolent | lazy |
| indomitable | unquestionable; certain |
| induce | to cause; to bring about |
| indulgence | gentle treatment; tolerance |
| inebriated | drunk |
| ineffable | not able to be described; unspeakable |
| ineluctable | inevitable; inescapable |
| inept | unfit; bungling; inefficient |
| inert | without power to move; inactive |