| A | B |
| ineffectual | adjective; unable to bring about a desired result; inadequate |
| inertia | noun; a tendency not to move, act, or change |
| infallible | adjective; free from error; absolutely reliable |
| influx | noun; a flowing in, as of people or things |
| inhibition | noun; the act of holding back; an inner belief, feeling, or force that checks one's actions, thoughts, or feelings; restraint |
| innate | adjective; inborn; inherent |
| innovation | noun; a new way to do something; something new |
| insipid | adjective; flavorless; dull or unexciting; lifeless |
| insolence | noun; quality or instance of being insulting and disrespectful; impudence |
| intermittent | adjective; stopping and starting with pauses between; occurring at irregular intervals; occasional |