Vocabulary builder I

ichthyic	adj.	Fish-like.
ichthyology	n.	The branch of zoology that treats of fishes.
ichthyosaurs	n.	A fossil reptile.
icily	adv.	Frigidly.
iciness	n.	The state of being icy.
icon	n.	An image or likeness.
iconoclast	n.	An image-breaker.
idealize	v.	To make to conform to some mental or imaginary standard.
idiom	n.	A use of words peculiar to a particular language.
idiosyncrasy	n.	A mental quality or habit peculiar to an individual.
idolize	v.	To regard with inordinate love or admiration.
ignoble	adj.	Low in character or purpose.
ignominious	adj.	Shameful.
Iliad	n.	A Greek epic poem describing scenes from the siege of Troy.
illegal	adj.	Not according to law.
illegible	adj.	Undecipherable.
illegitimate	adj.	Unlawfully begotten.
illiberal	adj.	Stingy.
illicit	adj.	Unlawful.
illimitable	adj.	Boundless.
illiterate	adj.	Having little or no book-learning.
ill-natured	adj.	Surly.
illogical	adj.	Contrary to the rules of sound thought.
illuminant	n.	That which may be used to produce light.
illuminate	v.	To supply with light.
illumine	v.	To make bright or clear.
illusion	n.	An unreal image presented to the senses.
illusive	adj.	Deceptive.
illusory	adj.	Deceiving or tending to deceive, as by false appearance.
imaginable	adj.	That can be imagined or conceived in the mind.
imaginary	adj.	Fancied.
imbibe	v.	To drink or take in.
imbroglio	n.	A misunderstanding attended by ill feeling, perplexity, or strife.
imbrue	v.	To wet or moisten.
imitation	n.	That which is made as a likeness or copy.
imitator	n.	One who makes in imitation.
immaculate	adj.	Without spot or blemish.
immaterial	adj.	Of no essential consequence.
immature	adj.	Not full-grown.
immeasurable	adj.	Indefinitely extensive.
immense	adj.	Very great in degree, extent, size, or quantity.
immerse	v.	To plunge or dip entirely under water or other fluid.
immersion	n.	The act of plunging or dipping entirely under water or another fluid.
immigrant	n.	A foreigner who enters a country to settle there.
immigrate	v.	To come into a country or region from a former habitat.
imminence	n.	Impending evil or danger.
imminent	adj.	Dangerous and close at hand.
immiscible	adj.	Separating, as oil and water.
immoral	adj.	Habitually engaged in licentious or lewd practices.
immortalize	v.	To cause to last or to be known or remembered throughout a great or indefinite length of time.
immovable	adj.	Steadfast.
immune	adj.	Exempt, as from disease.
immutable	adj.	Unchangeable.
impair	v.	To cause to become less or worse.
impalpable	adj.	Imperceptible to the touch.
impartial	adj.	Unbiased.
impassable	adj.	That can not be passed through or over.
impassible	adj.	Not moved or affected by feeling.
impassive	adj.	Unmoved by or not exhibiting feeling.
impatience	n.	Unwillingness to brook delays or wait the natural course of things.
impeccable	adj.	Blameless.
impecunious	adj.	Having no money.
impede	v.	To be an obstacle or to place obstacles in the way of.
impel	v.	To drive or urge forward.
impend	v.	To be imminent.
imperative	adj.	Obligatory.
imperceptible	adj.	Indiscernible.
imperfectible	adj.	That can not be perfected.
imperil	v.	To endanger.
imperious	adj.	Insisting on obedience.
impermissible	adj.	Not permissible.
impersonal	adj.	Not relating to a particular person or thing.
impersonate	v.	To appear or act in the character of.
impersuadable	adj.	Unyielding.
impertinence	n.	Rudeness.
imperturbable	adj.	Calm.
impervious	adj.	Impenetrable.
impetuosity	n.	Rashness.
impetuous	adj.	Impulsive.
impetus	n.	Any impulse or incentive.
impiety	n.	Irreverence toward God.
impious	adj.	Characterized by irreverence or irreligion.
implausible	adj.	Not plausible.
impliable	adj.	Capable of being inferred.
implicate	v.	To show or prove to be involved in or concerned
implicit	adj.	Implied.
imply	v.	To signify.
impolitic	adj.	Inexpedient.
importation	n.	The act or practice of bringing from one country into another.
importunate	adj.	Urgent in character, request, or demand.
importune	v.	To harass with persistent demands or entreaties.
impotent	adj.	Destitute of or lacking in power, physical, moral, or intellectual.
impoverish	v.	To make indigent or poor.
impracticable	adj.	Not feasible.
impregnable	adj.	That can not be taken by assault.
impregnate	v.	To make pregnant.
impromptu	n.	Anything done or said on the impulse of the moment.
improper	adj.	Not appropriate, suitable, or becoming.
impropriety	n.	The state or quality of being unfit, unseemly, or inappropriate.
improvident	adj.	Lacking foresight or thrift.
improvise	v.	To do anything extemporaneously or offhand.
imprudent	adj.	Heedless.
impudence	n.	Insolent disrespect.
impugn	v.	To assail with arguments, insinuations, or accusations.
impulsion	n.	Impetus.
impulsive	adj.	Unpremeditated.
impunity	n.	Freedom from punishment.
impure	adj.	Tainted.
impute	v.	To attribute.
inaccessible	adj.	Difficult of approach.
inaccurate	adj.	Not exactly according to the facts.
inactive	adj.	Inert.
inadequate	adj.	Insufficient.
inadmissible	adj.	Not to be approved, considered, or allowed, as testimony.
inadvertent	adj.	Accidental.
inadvisable	adj.	Unadvisable.
inane	adj.	Silly.
inanimate	adj.	Destitute of animal life.
inapprehensible	adj.	Not to be understood.
inapt	adj.	Awkward or slow.
inarticulate	adj.	Speechless.
inaudible	adj.	That can not be heard.
inborn	adj.	Implanted by nature.
inbred	adj.	Innate.
incandescence	n.	The state of being white or glowing with heat.
incandescent	adj.	White or glowing with heat.
incapacitate	v.	To deprive of power, capacity, competency, or qualification.
incapacity	n.	Want of power to apprehend, understand, and manage.
incarcerate	v.	To imprison.
incendiary	n.	Chemical or person who starts a fire-literally or figuratively.
incentive	n.	That which moves the mind or inflames the passions.
inception	n.	The beginning.
inceptive	adj.	Beginning.
incessant	adj.	Unceasing.
inchmeal	adv.	Piecemeal.
inchoate	adj.	Incipient.
inchoative	n.	That which begins, or expresses beginning.
incidence	n.	Casual occurrence.
incident	n.	A happening in general, especially one of little importance.
incidentally	adv.	Without intention.
incinerate	v.	To reduce to ashes.
incipience	n.	Beginning.
incipient	adj.	Initial.
incisor	n.	A front or cutting tooth.
incite	v.	To rouse to a particular action.
incitement	n.	That which moves to action, or serves as an incentive or stimulus.
incoercible	adj.	Incapable of being forced, constrained, or compelled.
incoherence	n.	Want of connection, or agreement, as of parts or ideas in thought, speech, etc.
incoherent	adj.	Not logically coordinated, as to parts, elements, or details.
incombustible	adj.	That can not be burned.
incomparable	adj.	Matchless.
incompatible	adj.	Discordant.
incompetence	n.	General lack of capacity or fitness.
incompetent	adj.	Not having the abilities desired or necessary for any purpose.
incomplete	adj.	Lacking some element, part, or adjunct necessary or required.
incomprehensible	adj.	Not understandable.
incompressible	adj.	Resisting all attempts to reduce volume by pressure.
inconceivable	adj.	Incomprehensible.
incongruous	adj.	Unsuitable for the time, place, or occasion.
inconsequential	adj.	Valueless.
inconsiderable	adj.	Small in quantity or importance.
inconsistent	adj.	Contradictory.
inconstant	adj.	Changeable.
incontrovertible	adj.	Indisputable.
inconvenient	adj.	Interfering with comfort or progress.
indefensible	adj.	Untenable.
indefinitely	adv.	In a vague or uncertain way.
indelible	adj.	That can not be blotted out, effaced, destroyed, or removed.
indescribable	adj.	That can not be described.
indestructible	adj.	That can not be destroyed.
indicant	adj.	That which points out.
indicator	n.	One who or that which points out.
indict	v.	To find and declare chargeable with crime.
indigence	n.	Poverty.
indigenous	adj.	Native.
indigent	adj.	Poor.
indigestible	adj.	Not digestible, or difficult to digest.
indigestion	n.	Difficulty or failure in the alimentary canal in changing food into absorptive nutriment.
indignant	adj.	Having such anger and scorn as is aroused by meanness or wickedness.
indignity	n.	Unmerited contemptuous conduct or treatment.
indiscernible	adj.	Not perceptible.
indiscreet	adj.	Lacking wise judgment.
indiscriminate	adj.	Promiscuous.
indispensable	adj.	Necessary or requisite for the purpose.
indistinct	adj.	Vague.
indivertible	adj.	That can not be turned aside.
indivisible	adj.	Not separable into parts.
indolence	n.	Laziness.
indolent	adj.	Habitually inactive or idle.
indomitable	adj.	Unconquerable.
induct	v.	To bring in.
indulgence	n.	The yielding to inclination, passion, desire, or propensity in oneself or another.
indulgent	adj.	Yielding to the desires or humor of oneself or those under one's care.
inebriate	v.	To intoxicate.
inedible	adj.	Not good for food.
ineffable	adj.	Unutterable.
inefficient	adj.	Not accomplishing an intended purpose.
inefficiency	n.	That which does not accomplish an intended purpose.
ineligible	adj.	Not suitable to be selected or chosen.
inept	adj.	Not fit or suitable.
inert	adj.	Inanimate.
inestimable	adj.	Above price.
inevitable	adj.	Unavoidable.
inexcusable	adj.	Not to be justified.
inexhaustible	adj.	So large or furnishing so great a supply as not to be emptied, wasted, or spent.
inexorable	adj.	Unrelenting.
inexpedient	adj.	Unadvisable.
inexpensive	adj.	Low-priced.
inexperience	n.	Lack of or deficiency in experience.
inexplicable	adj.	Such as can not be made plain.
inexpressible	adj.	Unutterable.
inextensible	adj.	Of unchangeable length or area.
infallible	adj.	Exempt from error of judgment, as in opinion or statement.
infamous	adj.	Publicly branded or notorious, as for vice, or crime.
infamy	n.	Total loss or destitution of honor or reputation.
inference	n.	The derivation of a judgment from any given material of knowledge on the ground of law.
infernal	adj.	Akin to or befitting hell or its occupants.
infest	v.	To be present in such numbers as to be a source of annoyance, trouble, or danger.
infidel	n.	One who denies the existence of God.
infidelity	n.	Disloyalty.
infinite	adj.	Measureless.
infinity	n.	Boundless or immeasurable extension or duration.
infirm	adj.	Lacking in bodily or mental strength.
infirmary	n.	A place for the reception or treatment of the sick.
infirmity	n.	A physical, mental, or moral weakness or flaw.
inflammable	adj.	Easily set on fire or excited.
inflammation	n.	A morbid process in some part of the body characterized by heat, swelling, and pain.
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.
intrigue	n.	A plot or scheme, usually complicated and intended to accomplish something by secret ways.
intrinsic	adj.	Inherent.
introductory	adj.	Preliminary.
introgression	n.	Entrance.
intromit	v.	To insert.
introspect	v.	To look into.
introspection	n.	The act of observing and analyzing one's own thoughts and feelings.
introversion	n.	The act of turning or directing inward, physically or mentally.
introvert	v.	To turn within.
intrude	v.	To come in without leave or license.
intrusion	n.	The act of entering without warrant or invitation; encroachment.
intuition	n.	Instinctive knowledge or feeling.
inundate	v.	To fill with an overflowing abundance.
inundation	n.	Flood.
inure	v.	To harden or toughen by use, exercise, or exposure.
invalid	adj.	Having no force, weight, or cogency.
invalid	n.	One who is disabled by illness or injury.
invalidate	v.	To render of no force or effect.
invaluable	adj.	Exceedingly precious.
invariable	adj.	Unchangeable.
invasion	n.	Encroachment, as by an act of intrusion or trespass.
invective	n.	An utterance intended to cast censure, or reproach.
inveigh	v.	To utter vehement censure or invective.
inventive	adj.	Quick at contrivance.
inverse	adj.	Contrary in tendency or direction.
inversion	n.	Change of order so that the first shall become last and the last first.
invert	v.	To turn inside out, upside down, or in opposite direction.
investigator	n.	One who investigates.
investor	n.	One who invests money.
inveterate	adj.	Habitual.
invidious	adj.	Showing or feeling envy.
invigorate	v.	To animate.
invincible	adj.	Not to be conquered, subdued, or overcome.
inviolable	adj.	Incapable of being injured or disturbed.
invoke	v.	To call on for assistance or protection.
involuntary	adj.	Unwilling.
involution	n.	Complication.
involve	v.	To draw into entanglement, literally or figuratively.
invulnerable	adj.	That can not be wounded or hurt.
inwardly	adv.	With no outward manifestation.
iota	n.	A small or insignificant mark or part.
irascible	adj.	Prone to anger.
irate	adj.	Moved to anger.
ire	n.	Wrath.
iridescence	n.	A many-colored appearance.
iridescent	adj.	Exhibiting changing rainbow-colors due to the interference of the light.
irk	v.	To afflict with pain, vexation, or fatigue.
irksome	adj.	Wearisome.
irony	n.	Censure or ridicule under cover of praise or compliment.
irradiance	n.	Luster.
irradiate	v.	To render clear and intelligible.
irrational	adj.	Not possessed of reasoning powers or understanding.
irreducible	adj.	That can not be lessened.
irrefragable	adj.	That can not be refuted or disproved.
irrefrangible	adj.	That can not be broken or violated.
irrelevant	adj.	Inapplicable.
irreligious	adj.	Indifferent or opposed to religion.
irreparable	adj.	That can not be rectified or made amends for.
irrepressible	adj.	That can not be restrained or kept down.
irresistible	adj.	That can not be successfully withstood or opposed.
irresponsible	adj.	Careless of or unable to meet responsibilities.
irreverence	n.	The quality showing or expressing a deficiency of veneration, especially for sacred things.
irreverent	adj.	Showing or expressing a deficiency of veneration, especially for sacred things.
irreverential	adj.	Showing or expressing a deficiency of veneration, especially for sacred things.
irreversible	adj.	Irrevocable.
irrigant	adj.	Serving to water lands by artificial means.
irrigate	v.	To water, as land, by ditches or other artificial means.
irritable	adj.	Showing impatience or ill temper on little provocation.
irritancy	n.	The quality of producing vexation.
irritant	n.	A mechanical, chemical, or pathological agent of inflammation, pain, or tension.
irritate	v.	To excite ill temper or impatience in.
irruption	n.	Sudden invasion.
isle	n.	An island.
islet	n.	A little island.
isobar	n.	A line joining points at which the barometric pressure is the same at a specified moment.
isochronous	adj.	Relating to or denoting equal intervals of time.
isolate	v.	To separate from others of its kind.
isothermal	adj.	Having or marking equality of temperature.
itinerant	adj.	Wandering.
itinerary	n.	A detailed account or diary of a journey.
itinerate	v.	To wander from place to place.