| incandescent | Emitting light as a result of being heated | |
| incensed | Very angry; enraged | |
| inchoate | just begun and so not fully formed or developed; rudimentary | |
| incipient | In an initial stage; beginning to happen or develop | |
| incoherent | Not able to be understood; nonsensical. | |
| inculcate | To instill (an attitude, idea, or habit) by persistent instruction | |
| incumbent | Noun: a person who currently holds a particular position or office | |
| indefatigable | Incapable of being tired out; not yielding to fatigue; untiring. | |
| indictment | A formal charge or accusation of a serious crime | |
| indigenous | Originating or occurring naturally in a particular place; native | |