| Term | Definition |
| iconoclast | person who attacks popular beliefs |
| idiosyncrasy | personal mannerism |
| idolatry | excessive admiration of |
| idyll | a carefree episode or experience |
| ignoble | dishonorable common undignified |
| ignominious | shameful dishonorable undignified disgraceful |
| illicit | unlawful forbidden |
| imbroglio | complicated and embarrassing situation |
| immaculate | pure faultless |
| imminent | likely to come or happen soon |
| immutable | that cannot be changed |
| impair | worsen diminish in value |
| impassive | unmoved feeling no sign of passion |
| impecunious | having little or no money |
| impede | hinder get in the way of |
| impediment | something that hinders (e.g. stammer) |
| impending | imminent being about to happen expected |
| imperative | urgent essential |
| imperious | commanding haughty arrogant |
| impermeable | that cannot be permeated |
| imperturbable | calm not capable of being excited |
| impervious | not allowing to pass through (of materials) |
| imperiousness | haughty arrogant commanding |
| impetuous | having sudden energy impulsive thrusting ahead forceful |
| impiety | lack of reverence or dutifulness |
| implacable | incapable of being placated unpleasable |
| implicate | show that smb has a share |
| implicit | implied though not plainly expressed |
| implosion | collapse bursting inward |
| importune | beg urgently solicit (of a prostitute) |
| imprecation | an invocation of evil a curse |
| impromptu | without preparation |
| impudent | rash indiscreet |
| impugned | challenged to be doubted |
| impute | to attribute to a cause or source ascribe |
| inadvertent | not paying proper attention |
| inane | silly senseless |
| inasmuch | since because |
| incense | make angry |
| incessant | often repeated continual |
| inchoate | not yet fully formed rudimentary elementary |
| incipient | beginning |
| incise | engrave make a cut in |
| incite | stir up rouse |
| inclined | directing the mind in a certain direction |
| incongruous | out of place not in harmony or agreement |
| incorrigibility | cannot be cured or corrected |
| incredulous | skeptical unwilling to believe |
| inculcate | fix firmly by repetition |
| incumbents | official duties |
| incursion | a raid a sudden attack |
| indefatigability | not easily exhaustible tirelessness |
| indelible | that cannot be rubbed out |
| indigence | poverty |
| indigenous | native |
| indistinct | not easily heard seen clearly marked |
| indolence | laziness |
| indomitable | not easily discouraged or subdued |
| indulge | gratify give way to satisfy allow oneself |
| indulgent | inclined to indulge |
| ineffable | to great to be described in words |
| ineluctable | certain inevitable |
| inept | unskillful said or done at the wrong time |
| ineptitude | quality of being unskillful |
| inferno | hell |
| infuriate | fill with fury or rage |
| infuse | put pour fill |
| ingenuous | naive young artless frank honest sincere |
| ingest | take in by swallowing |
| inimical | harmful or unfriendly |
| inimitable | defying imitation unmatchable |
| innocuous | causing no harm |
| inscrutable | incapable of being discovered or understood |
| insensible | unconscious unresponsive unaffected |
| insinuate | suggest unpleasantly make a way for something gently |
| insipid | without taste or flavor |
| insouciant | unconcerned carefree |
| insularity | narrow-mindedness isolated |
| insurrection | rising of people to open resistance to |
| interdict | prohibit forbid |
| interim | as an installment |
| intersperse | place here and there |
| intransigence | unwillingness to compromise stubbornness intractability |
| intransigent | uncompromising |
| intrepid | fearless brave undaunted |
| introspection | examining one's own thoughts and feelings |
| inundate | flood cover by overflowing |
| inured | accustomed to adapted |
| invective | abusive language curses |
| inveigh | to attack verbally denounce deprecate |
| inveterate | deep-rooted. long-established |
| invincible | too strong to be defeated |
| involute | complex |
| irascible | irritable easily angered |
| irate | angry |
| ire | anger |
| irksome | tiresome |
| irresolute | hesitating undecided |
| irrevocable | final and unalterable |
| itinerate | to travel from place to place to peregrinate |