inflexible adj. That can not be altered or varied.
influence n. Ability to sway the will of another.
influential adj. Having the power to sway the will of another.
influx n. Infusion.
infrequence n. Rareness.
infrequent adj. Uncommon.
infringe v. To trespass upon.
infuse v. To instill, introduce, or inculcate, as principles or qualities.
infusion n. The act of imbuing, or pouring in.
ingenious adj. Evincing skill, originality, or cleverness, as in contrivance or arrangement.
ingenuity n. Cleverness in contriving, combining, or originating.
ingenuous adj. Candid, frank, or open in character or quality.
inglorious adj. Shameful.
ingraft v. To set or implant deeply and firmly.
ingratiate v. To win confidence or good graces for oneself.
ingratitude n. Insensibility to kindness.
ingredient n. Component.
inherence n. The state of being permanently existing in something.
inherent adj. Intrinsic.
inhibit v. To hold back or in.
inhospitable adj. Not disposed to entertain strangers gratuitously.
inhuman adj. Savage.
inhume v. To place in the earth, as a dead body.
inimical adj. Adverse.
iniquity n. Gross wrong or injustice.
initiate v. To perform the first act or rite.
inject v. To introduce, as a fluid, by injection.
injunction n. Mandate.
inkling n. A hint.
inland adj. Remote from the sea.
inlet n. A small body of water leading into a larger.
inmost adj. Deepest within.
innocuous adj. Harmless.
innovate v. To introduce or strive to introduce new things.
innuendo n. Insinuation.
innumerable adj. Countless.
inoffensive adj. Causing nothing displeasing or disturbing.
inopportune adj. Unsuitable or inconvenient, especially as to time.
inquire v. To ask information about.
inquisition n. A court or tribunal for examination and punishment of heretics.
inquisitive adj. Given to questioning, especially out of curiosity.
inquisitor n. One who makes an investigation.
inroad n. Forcible encroachment or trespass.
insatiable adj. That desires or craves immoderately or unappeasably.
inscribe v. To enter in a book, or on a list, roll, or document, by writing.
inscrutable adj. Impenetrably mysterious or profound.
insecure adj. Not assured of safety.
insensible adj. Imperceptible.
insentient adj. Lacking the power of feeling or perceiving.
inseparable adj. That can not be separated.
insidious adj. Working ill by slow and stealthy means.
insight n. Intellectual discernment.
insignificance n. Lack of import or of importance.
insignificant adj. Without importance, force, or influence.
insinuate v. To imply.
insipid adj. Tasteless.
insistence n. Urgency.
insistent adj. Urgent.
insolence n. Pride or haughtiness exhibited in contemptuous and overbearing treatment of others.
insolent adj. Impudent.
insomnia n. Sleeplessness.
inspector n. An official appointed to examine or oversee any matter of public interest or importance.
instance n. A single occurrence or happening of a given kind.
instant n. A very brief portion of time.
instantaneous adj. Done without perceptible lapse of time.
instigate v. To provoke.
instigator n. One who incites to evil.
instill v. To infuse.
instructive adj. Conveying knowledge.
insufficiency n. Inadequacy.
insufficient adj. Inadequate for some need, purpose, or use.
insular adj. Pertaining to an island.
insulate v. To place in a detached state or situation.
insuperable adj. Invincible.
insuppressible adj. Incapable of being concealed.
insurgence n. Uprising.
insurgent n. One who takes part in forcible opposition to the constituted authorities of a place.
insurrection n. The state of being in active resistance to authority.
intangible adj. Not perceptible to the touch.
integrity n. Uprightness of character and soundness of moral principle.
intellect n. The faculty of perception or thought.
intellectual adj. Characterized by intelligence.
intelligence n. Capacity to know or understand.
intelligible adj. Comprehensible.
intemperance n. Immoderate action or indulgence, as of the appetites.
intension n. The act of stringing or stretching, or state of being strained.
intensive adj. Adding emphasis or force.
intention n. That upon which the mind is set.
interact v. To act reciprocally.
intercede v. To mediate between persons.
intercept v. To interrupt the course of.
intercession n. Entreaty in behalf of others.
intercessor n. A mediator.
interdict n. Authoritative act of prohibition.
interim n. Time between acts or periods.
interlocutor n. One who takes part in a conversation or oral discussion.
interlude n. An action or event considered as coming between others of greater length.
intermediate adj. Being in a middle place or degree or between extremes.
interminable adj. Having no limit or end.
intermission n. A recess.
intermit v. To cause to cease temporarily.
intermittent adj. A temporary discontinuance.
interpolation n. Verbal interference.
interpose v. To come between other things or persons.
interposition n. A coming between.
interpreter n. A person who makes intelligible the speech of a foreigner by oral translation.
interrogate v. To examine formally by questioning.
interrogative adj. Having the nature or form of a question.
interrogatory n. A question or inquiry.
interrupt v. To stop while in progress.
intersect v. To cut through or into so as to divide.
intervale n. A low tract of land between hills, especially along a river.
intervene v. To interfere for some end.
intestacy n. The condition resulting from one's dying not having made a valid will.
intestate adj. Not having made a valid will.
intestine n. That part of the digestive tube below or behind the stomach, extending to the anus.
intimacy n. Close or confidential friendship.
intimidate v. To cause to become frightened.
intolerable adj. Insufferable.
intolerance n. Inability or unwillingness to bear or endure.
intolerant adj. Bigoted.
intoxicant n. Anything that unduly exhilarates or excites.
intoxicate v. To make drunk.
intracellular adj. Occurring or situated within a cell.
intramural adj. Situated within the walls of a city.
intrepid adj. Fearless and bold.
intricacy n. Perplexity.
intricate adj. Difficult to follow or understand.