| Term | Definition |
| immaculate | spotless; flawless; absolutely clean |
| imminent | near at hand; impending |
| immobility | state of being immovable |
| immolate | offer as sacrifice |
| immune | resistant to; free or exempt from |
| immure | imprison; shut up in confinement |
| immutable | unchangeable |
| impair | injure; hurt |
| impale | pierce |
| impalpable | imperceptible |
| impartial | not biased; fair |
| impassable | not able to be traveled or crossed |
| impasse | predicament from which there is no escape |
| impassive | without feeling |
| impeach | charge with crime in office; indict |
| impeccable | faultless |
| impecunious | without money |
| impede | hinder; block |
| impediment | hindrance; stumbling block |
| impel | drive or force onward |
| impenetrable | not able to be pierced or entered |
| impenitent | not repentant |
| imperative | absolutely necessary; critically important |
| imperceptible | unnoticeable; undetectable |
| imperial | like an emperor; related to an empire |
| imperious | domineering; haughty |
| impermeable | impervious; not permitting passage through its substance |
| impertinent | insolent; rude |
| imperturbable | calm; placid |
| impervious | impenetrable; incapable of bieng damaged |
| impetuous | violent; hasty; rash |
| impetus | moving force; incentive; stimulus |
| impiety | irreverence; lack of respect for god |
| impinge | imfringe; touch; collide with |
| impious | irreverent |
| implacable | incapable of being pacified |
| implausible | unlikely; unbelievable |
| implement | put into effect; supply with tools |
| implicate | incriminate; show to be involved |
| implication | something hintedor suggested |
| implicit | understood but not stated |
| implode | burst inward |
| implore | beg |
| imply | suggest a meaning not expressed; signify |
| impolitic | not wise |
| imponderable | weightless |
| import | significance |
| importunate | urging; demanding |
| importune | beg persistently |
| imposture | assuming a false identity |
| impotent | weak; ineffective |
| imprecation | curse |
| impregnable | invulnerable |
| impromptu | without previous preparation; off the cuff; on the spur of moment |
| impropriety | improperness; unsuitableness |
| improvident | thriftless |
| improvise | compose on the spur of the moment |
| imprudent | lacking caution; injudicious |
| impudence | impertinence; insolence |
| impugn | dispute or contradict |
| impuissance | powerlessness; feebleness |
| impunity | freedom from punishment or harm |
| impute | attribute; ascribe |
| inadvertently | unintentionaly; by oversight |
| inalienable | not to be taken away |
| inane | silly; senseless |
| inanimate | lifeless |
| inarticulate | speechless; producing indistinct speech |
| inaugurate | begin formally; install in office |
| incandescent | strikingly bright; shining with intense heat |
| incantation | singing or chanting of magic spells |
| incapacitate | disable |
| incarcerate | imprison |
| incarnate | endowed with flesh; personified |
| incarnation | act of assuming a human body and human nature |
| incendiary | arsonist |
| incense | enrage; infuriate |
| incentive | spur; motive |
| inception | start |
| incessant | uninterrupted; unceasing |