| impenetrable | Impossible to pass through or enter | |
| impeded | Delay or prevent (someone or something) by obstructing them; hinder. | |
| impecunious | Having little or no money; penniless; poor | |
| impeccable | In accordance with the highest standards; faultless | |
| impassive | Not feeling or showing emotion | |
| immure | To enclose or confine (someone) against their will | |
| imminent | About to happen | |
| imbroglio | An extremely confused, complicated, or embarrassing situation | |
| illiberal | Opposed to liberal principles; restricting freedom of thought or behavior | |
| ignominy | Public shame or disgrace | |