Page 12 of 25
| Ingénue | naïve, unsophisticated person |
| Ingrate | ungrateful person |
| Inimical | hostile |
| Innate | inherited; inborn |
| Innocuous | harmless; inoffensive |
| Innovate | create; introduce something new |
| Inscrutable | mysterious; impenetrable |
| Insentient | unfeeling |
| Insipid | dull; bland; boring |
| Instigate | to start; provoke |
| Instigator | troublemaker; person who entices others to do something |
| Insurgent | a rebel |
| Interminable | never-ending |
| Intermittent | sporadic; irregular |
| Intransigence | stubbornness |
| Intransigent | stubborn; unyielding |
| Intrepid | brave |
| Inveterate | habitual |
| Invidious | arousing envy |
| Inviolable | cannot be invaded |