immobile
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C1 adjective /ɪˈmoʊbəl/

immobile

inmóvil
Meaning
unable to move or be moved
Example
After the accident, he was immobile for weeks.
Después del accidente, estuvo inmóvil durante semanas.
C1 adjective /ˌɪnədˈvaɪzəbl/

inadvisable

desaconsejable
Meaning
Not recommended; likely to have undesirable consequences.
Example
It is inadvisable to drive in such heavy rain.
No es recomendable conducir bajo tal lluvia intensa.
C1 adjective /ˌɪndɪˈfɛnsəbl̩/

indefensible

indefendible
Meaning
not able to be protected or justified
Example
The minister’s remarks were considered indefensible by the public.
Los comentarios del ministro fueron considerados indefendibles por el público.
C1 noun /ˈɪrɪtənt/

irritant

sustancia irritante
Meaning
something that causes irritation or discomfort
Example
Dust is a common irritant for people with allergies.
El polvo es un irritante común para las personas con alergias.
C1 adjective ɪnˈkʌm.bənt

incumbent

obligatorio
Meaning
necessary for (someone) as a duty or responsibility.
Example
It is incumbent upon all citizens to obey the law.
Es obligatorio para todos los ciudadanos obedecer la ley.
C1 verb /ɪnˈvɜːrt/

invert

invertir
Meaning
To turn something upside down or in the opposite position, order, or direction.
Example
He inverted the glass to let the water drain out.
Él invirtió el vaso para dejar que el agua se drenara.
C1 adjective /ɪˈlʌstriəs/

illustrious

ilustre
Meaning
Well known, respected, and admired for past achievements.
Example
She had an illustrious career in medicine.
Tuvo una carrera ilustre en la medicina.
C1 adjective /ˌɪntərˈtwaɪnd/

intertwined

felicidad
Meaning
closely connected or twisted together
Example
Their lives became deeply intertwined after the accident.
Ella no pudo ocultar su felicidad cuando recibió el premio.
C1 adjective /ˌɪnsərˈmaʊntəbl/

insurmountable

insuperable
Meaning
Too great to be overcome.
Example
The explorers faced insurmountable odds in the desert.
Los exploradores enfrentaron obstáculos insuperables en el desierto.
C1 adjective /ˌɪndɪˈspjuːtəbəl/

Indisputable

indiscutible; innegable; cierto
Meaning
impossible to deny or argue against; undeniable; certain
Example
The evidence against him was indisputable.
La evidencia en su contra era indiscutible.
C1 noun /ɪˈmɜː.ʃən/

immersion

inmersión
Meaning
Complete engagement in an environment or experience.
Example
Immersion in VR games makes users feel like they are inside the virtual world.
La inmersión en juegos de VR hace que los usuarios sientan como si estuvieran dentro del mundo virtual.
C1 noun /ɪmˈpɜː.mə.nəns/

impermanence

impermanencia
Meaning
The state or fact of lasting for only a limited period of time.
Example
The philosophy of Buddhism emphasizes the impermanence of life.
La filosofía del budismo enfatiza la impermanencia de la vida.
C1 adjective /ˌɪnɪkˈsplɪkəbl/

inexplicable

inexplicable
Meaning
Impossible to explain or understand.
Example
The sudden disappearance of the file was inexplicable.
La repentina desaparición del archivo fue inexplicable.
C1 adjective ɪnˈdʒiː.ni.əs

ingenious

ingenioso
Meaning
Showing inventiveness and skill; clever, original, and inventive.
Example
His ingenious ideas transformed modern physics.
Sus ideas ingeniosas transformaron la física moderna.
C1 adjective /ɪnˈvɑːlənˌtɛri/

involuntary

involuntario
Meaning
done without will or conscious control
Example
He gave an involuntary shiver when he heard the loud noise.
Él dio un escalofrío involuntario cuando escuchó el ruido fuerte.
C1 adjective /ˌɪnədˈvɜːrtənt/

inadvertent

inadvertido, no intencionado
Meaning
Not resulting from or achieved through deliberate planning; unintentional.
Example
Her inadvertent mistake caused a delay in the project.
Su error inadvertido causó un retraso en el proyecto.
C1 adjective /ˌɪntərˈtʃeɪndʒəbl/

interchangeable

intercambiable
Meaning
able to be exchanged with each other without difference or loss of function
Example
These machine parts are interchangeable, so they can be replaced easily.
Estas piezas de la máquina son intercambiables, por lo que se pueden reemplazar fácilmente.
C1 noun /ɪˈrɛlɪvənsi/

irrelevancy

irrelevancia
Meaning
the state of being unrelated or unimportant to the matter at hand
Example
The judge dismissed the argument because of its irrelevancy to the case.
El juez rechazó el argumento por su irrelevancia para el caso.
C1 adjective /ɪnˈveɪsɪv/

invasive

invasivo
Meaning
Tending to spread harmfully, intruding aggressively, or encroaching beyond proper boundaries.
Example
The doctor explained that the procedure was minimally invasive.
El doctor explicó que el procedimiento era mínimamente invasivo.
C1 adjective /ˌɪmprɪˈsaɪs/

imprecise

impreciso
Meaning
Not exact or accurate; vague.
Example
His explanation was too imprecise to be helpful.
Su explicación era demasiado imprecisa para ser útil.
C1 adjective ɪn ˈfleɪ.ʃə.ner.i

inflationary

inflacionario
Meaning
Characterized by or tending to cause monetary inflation; relating to rising prices.
Example
The government took measures to control inflationary pressures.
El gobierno tomó medidas para controlar las presiones inflacionarias.
C1 noun /ɪmˈpɛd.ɪ.mənt/

impediment

obstáculo
Meaning
A hindrance or obstruction in doing something; something that prevents progress.
Example
Lack of funds is a major impediment to the project.
La falta de fondos es un gran obstáculo para el proyecto.
C1 adjective /ˌɪnkənˈkluːsɪv/

inconclusive

inconcluso
Meaning
Not leading to a definite result or decision.
Example
The investigation remained inconclusive due to a lack of evidence.
La investigación permaneció inconclusa debido a la falta de evidencia.
C1 noun /ˌɪm.pəˈzɪʃ.ən/

Imposition

imposición; carga; demanda injusta
Meaning
the action or process of imposing something or of being imposed; an unfair burden or demand
Example
The imposition of new taxes without consultation angered the citizens greatly.
La imposición de nuevos impuestos sin consulta enfureció enormemente a los ciudadanos.
C1 verb /ɪnˈtruːd/

intrude

interrumpir
Meaning
To enter a place or situation where one is not wanted or not invited.
Example
He felt embarrassed to intrude on their private conversation.
Él se sintió avergonzado de interrumpir su conversación privada.
C1 adjective /aɪˈreɪt/

irate

iracundo
Meaning
Extremely angry.
Example
The customer became irate after waiting for hours.
El cliente se puso iracundo después de esperar durante horas.
C1 verb /ɪmˈpiːtʃ/

impeach

impeachar
Meaning
To charge a public official with misconduct while in office.
Example
The parliament voted to impeach the president.
El parlamento votó para impugnar al presidente.
C1 noun /ˌɪnkjʊˈbeɪʃən/

incubation

el proceso de mantener huevos, células u organismos en las condiciones adecuadas para su desarrollo
Meaning
the process of keeping eggs, cells, or organisms in the right conditions for development
Example
The incubation of the eggs lasted for three weeks.
La incubación de los huevos duró tres semanas.
C1 verb /ɪmˈpɛl/

impel

impulsar
Meaning
to drive, force, or urge someone to do something
Example
Her curiosity impelled her to open the mysterious box.
Su curiosidad la impulsó a abrir la caja misteriosa.
C1 noun /ˌɪn.trəˈspek.ʃən/

introspection

introspección
Meaning
The examination or observation of one's own mental and emotional processes; self-reflection.
Example
Through introspection, she gained insight into her emotions.
A través de la introspección, obtuvo una visión profunda de sus emociones.
C1 noun /ɪnˈfjuːʒən/

infusion

infusión
Meaning
the act of introducing something into another; a drink made by steeping leaves or herbs in liquid
Example
She prepared a calming infusion of chamomile tea.
Ella preparó una infusión calmante de té de manzanilla.
C1 adjective /ɪnˈstɪŋk.tɪv/

instinctive

instintivo, natural, automático
Meaning
Based on instinct; done without conscious thought; natural and automatic.
Example
His instinctive reaction saved his life.
Su reacción instintiva le salvó la vida.
C1 noun /ˈɪmɪdʒəri/

imagery

imaginería
Meaning
visually descriptive or figurative language, especially in a literary work
Example
The poet's use of imagery brought the scene to life.
El uso de imaginería por el poeta dio vida a la escena.
C1 noun (plural) /ˈɪndɪˌsiːz/

indices

índices
Meaning
plural form of index; statistical measures or reference points used for comparison
Example
Stock market indices fell sharply after the announcement.
Los índices del mercado de valores cayeron drásticamente después del anuncio.
C1 verb /ɪnˈskraɪb/

inscribe

grabar
Meaning
to write or carve words or symbols on a surface
Example
They inscribed her name on the trophy.
Ellos grabaron su nombre en el trofeo.
C1 noun /ˌɪnɪkˈspɪəriəns/

inexperience

inexperiencia
Meaning
Lack of knowledge or skill in a particular activity or field.
Example
His inexperience in handling negotiations was evident.
Su inexperiencia en las negociaciones era evidente.
C1 verb /ɪnˈfleɪm/

inflame

inflamar
Meaning
to arouse strong feelings or provoke anger; to cause inflammation in the body
Example
The politician's remarks served to inflame public opinion.
Las declaraciones del político sirvieron para inflamar la opinión pública.
C1 noun ɪmˈpɛə(r)mənt

impairment

daño, discapacidad
Meaning
The state of being damaged or weakened; a disability or handicap.
Example
Hearing impairment can be caused by long-term exposure to loud noise.
La pérdida auditiva puede ser causada por la exposición prolongada a ruidos fuertes.
C1 noun /ˌɪnkoʊˈhɪrəns/

incoherence

incoherencia
Meaning
The quality of being unclear, confused, or lacking logical connection.
Example
His speech was full of incoherence and difficult to follow.
Su discurso estaba lleno de incoherencias y era difícil de seguir.
C1 adjective /ɪmˈpɜːmiəbl/

impermeable

impermeable
Meaning
Not allowing fluid or gas to pass through.
Example
The container is made of impermeable plastic.
El contenedor está hecho de plástico impermeable.
C1 noun /ˈɪn.trə.vɜːrt/

introvert

introvertido
Meaning
A person who tends to be shy and prefers spending time alone rather than in groups.
Example
As an introvert, he preferred reading over attending parties.
Como introvertido, prefería leer en lugar de asistir a fiestas.
C1 verb /ɪnˈfjuːz/

infuse

infundir
Meaning
to fill or spread through something; to instill a quality, idea, or feeling
Example
The teacher tried to infuse her students with a love for reading.
La profesora trató de infundir a sus estudiantes con un amor por la lectura.
C1 noun /ˌɪn.səˌbɔːr.dɪˈneɪ.ʃən/

insubordination

insubordinación
Meaning
Defiance of authority; refusal to obey orders.
Example
The soldier was punished for insubordination during the mission.
El soldado fue castigado por insubordinación durante la misión.
C1 adjective /ˈɪnərmoʊst/

Innermost

más profundo; más personal
Meaning
most private and secret; deepest; most personal
Example
She shared her innermost feelings with her closest friend.
Ella compartió sus sentimientos más profundos con su amigo más cercano.
C1 adjective /ɪmˈpɑːrʃəl/

Impartial

imparcial; neutral
Meaning
treating all sides fairly; unbiased; neutral
Example
A good judge must remain impartial throughout the trial.
Un buen juez debe mantenerse imparcial durante todo el juicio.
C1 adjective ɪnɪɡˈzɔːstɪbəl

inexhaustible

inagotable
Meaning
Unable to be used up or worn out; limitless.
Example
His inexhaustible energy allowed him to work tirelessly on his projects.
Su energía inagotable le permitió trabajar incansablemente en sus proyectos.
C1 adjective /ˌɪnsɪˈdɛntəl/

incidental

incidental
Meaning
happening as a minor part or in connection with something else
Example
Incidental expenses like snacks and tips were included in the bill.
Gastos incidentales como bocadillos y propinas fueron incluidos en la factura.
C1 verb /ɪmˈpɪndʒ/

impinge

afectar
Meaning
to have an effect or impact on something; to encroach or infringe
Example
The noise from the construction site impinges on our daily activities.
El ruido de la construcción afecta nuestras actividades diarias.
C1 noun /ɪmˈpjʊərəti/

impurity

impureza
Meaning
the state of being unclean or contaminated; a substance that makes something impure
Example
The scientist removed every impurity from the water sample.
El científico eliminó toda impureza de la muestra de agua.
C1 verb /ɪnˈkrɪmɪˌneɪt/

incriminate

incriminar
Meaning
to make someone appear guilty of a crime or wrongdoing
Example
The new evidence could incriminate the suspect in the robbery case.
La nueva evidencia podría incriminar al sospechoso en el caso de robo.
C1 adjective /ˌɪnkənˈsiːvəbl̩/

inconceivable

inconcebible
Meaning
Impossible to imagine or believe; beyond comprehension.
Example
It seemed inconceivable that she could finish the marathon after such little training.
Parecía inconcebible que ella pudiera terminar el maratón después de tan poco entrenamiento.
C1 noun /ɪˈreləvəns/

irrelevance

irrelevancia
Meaning
the quality of not being connected to or important for a particular matter; lack of significance
Example
His long explanation only highlighted the irrelevance of the details to the main issue.
Su larga explicación solo resaltó la irrelevancia de los detalles para el tema principal.
C1 adjective /ˈɪɡ.ni.əs/

igneous

ígnea
Meaning
Formed through the cooling and solidification of magma or lava.
Example
Granite is an igneous rock commonly used in construction.
El granito es una roca ígnea que se utiliza comúnmente en la construcción.
C1 adjective /ɪnˈvɛntɪv/

inventive

inventivo
Meaning
Having the ability to create or design new things or to think originally.
Example
The inventor was known for his inventive solutions to everyday problems.
El inventor era conocido por sus soluciones inventivas para los problemas cotidianos.
C1 noun /ˌɪrɪˌspɒnsəˈbɪləti/

irresponsibility

irresponsabilidad
Meaning
lack of responsibility or accountability; failure to act in a reliable or sensible way
Example
The accident was caused by his irresponsibility at work.
El accidente fue causado por su irresponsabilidad en el trabajo.
C1 verb /ˈɪtəreɪt/

iterate

iterar
Meaning
To repeat a process or statement, often to improve or refine.
Example
The software team will iterate the design until it meets user needs.
El equipo de software iterará el diseño hasta que cumpla con las necesidades del usuario.
C1 verb /ɪnˈklaɪn/

incline

inclinarse
Meaning
to feel willing or favorably disposed toward something; to bend or tilt
Example
She is inclined to agree with the proposal.
Ella está inclinada a estar de acuerdo con la propuesta.
C1 verb /ɪnˈkɜːr/

incur

incurrir
Meaning
To bring upon oneself something undesirable, usually as a result of actions.
Example
He incurred a fine for parking in the wrong place.
Él incurrió en una multa por aparcar en el lugar equivocado.
C1 noun /ˌɪn.trəˈvɜːr.ʒən/

introversion

introversión
Meaning
The tendency to be inward-looking and shy, preferring solitary activities.
Example
Her introversion made it difficult for her to enjoy large parties.
Su introversión le dificultaba disfrutar de las grandes fiestas.
C1 adjective /ɪnˈtɒl.ər.ə.bəl/

Intolerable

intolerable
Meaning
unable to be endured; extremely unpleasant or painful
Example
The noise from the construction site was intolerable.
El ruido de la obra de construcción era intolerable.
C1 noun /ɪnˈsæn.ə.ti/

Insanity

locura; demencia
Meaning
the state of being seriously mentally ill; extreme foolishness or irrationality
Example
The defense lawyer argued that his client was not guilty by reason of insanity.
El abogado defensor argumentó que su cliente no era culpable por razón de locura.
C1 noun /ˌɪndɪˈdʒɛstʃən/

indigestion

indigestión
Meaning
Discomfort or pain in the stomach associated with difficulty in digesting food.
Example
He avoided spicy food because it often gave him indigestion.
Él evitó la comida picante porque a menudo le provocaba indigestión.
C1 verb ɪˈnɔː.ɡjə.reɪ.tɪd

inaugurated

inaugurado
Meaning
Begin or introduce (a system, policy, or period) formally.
Example
The organization was inaugurated officially.
La organización fue inaugurada oficialmente.
C1 adjective /ˌɪnkənˈsɪdərət/

inconsiderate

desconsiderado
Meaning
Thoughtless; showing a lack of concern for others.
Example
It was inconsiderate of him to play loud music late at night.
Fue desconsiderado de su parte poner música alta tarde en la noche.
C1 adverb /ˌɪnsɪˈdɛntəli/

incidentally

por cierto
Meaning
by the way; used to introduce a remark not directly related to the main subject
Example
Incidentally, did you know that she studied in Paris?
Por cierto, ¿sabías que estudió en París?
C1 adjective ˌɪn.təˈstel.ər

interstellar

entre las estrellas, interestelar, cósmico
Meaning
Occurring or situated between stars.
Example
Scientists study interstellar travel possibilities.
Los científicos estudian las posibilidades de viajes interestelares.
C1 adjective /ˌɪndɪˈstɪŋkt/

indistinct

indistinto
Meaning
Not clear or sharply defined; vague or blurred.
Example
The sound of voices was indistinct in the distance.
El sonido de las voces era indistinto a lo lejos.
C1 adjective /ˈɪndɪɡoʊ bluː/

Indigo-blue

azul índigo
Meaning
a deep blue color with a purplish tinge
Example
The indigo-blue sky looked magnificent at twilight.
El cielo azul índigo se veía magnífico al atardecer.
C1 adjective /ˌɪnɪkˈskjuːzəbl/

inexcusable

inexcusable
Meaning
Too bad to be justified or overlooked; unforgivable.
Example
His rude behavior was inexcusable.
Su comportamiento grosero era inexcusable.
C1 verb /ˌɪntəˈsɛkt/

intersect

intersectar
Meaning
to cross or pass through each other
Example
The two roads intersect at the city center.
Los dos caminos se intersectan en el centro de la ciudad.
C1 adjective /ˌɪnstənˈteɪniəs/

instantaneous

instantáneo
Meaning
Happening immediately, without any delay.
Example
The change in temperature was almost instantaneous.
El cambio de temperatura fue casi instantáneo.
C1 adjective ɪnˈtrɪn.zɪk

intrinsic

intrínseco, esencial, natural
Meaning
Belonging naturally; essential. Existing as a natural or basic part of something.
Example
Creativity is an intrinsic quality of a great artist.
La creatividad es una cualidad intrínseca de un gran artista.
C1 adjective /ɪnˈvɪnsəbl/

invincible

invencible
Meaning
too powerful to be defeated or overcome
Example
The team seemed invincible after winning ten matches in a row.
El equipo parecía invencible después de ganar diez partidos consecutivos.
C1 noun /ɪnˈtɛstɪn/

intestine

intestino
Meaning
The part of the digestive system where food is digested and absorbed, extending from the stomach to the anus.
Example
The doctor explained how nutrients are absorbed in the small intestine.
El doctor explicó cómo los nutrientes se absorben en el intestino delgado.
C1 adjective /ɪmˈpæsɪv/

impassive

impasible
Meaning
Not showing or feeling emotion; expressionless.
Example
Despite the shocking news, she remained impassive.
A pesar de las noticias impactantes, ella permaneció impasible.
C1 adjective /ɪnˈdefɪnət/

Indefinite

indefinido
Meaning
not clearly defined; uncertain; vague; unlimited in time
Example
The meeting has been postponed for an indefinite period.
La reunión se ha pospuesto por un período indefinido.
C1 noun ˌɪndɪˈspensəbl̩ ˈkɒmpɪtənsi

indispensable competency

competencia indispensable
Meaning
Essential skill or ability that cannot be done without; a crucial capability that is absolutely necessary.
Example
Digital literacy is an indispensable competency in the 21st century.
La alfabetización digital es una competencia indispensable en el siglo XXI.
C1 noun /ˈɪmɪnəns/

imminence

inminencia, estado de proximidad
Meaning
the state of being about to happen
Example
The imminence of the storm forced people to take shelter.
La inminencia de la tormenta obligó a la gente a buscar refugio.
C1 noun /ɪnˈækjʊrəsi/

inaccuracy

inexactitud
Meaning
lack of accuracy or precision; an incorrect or wrong detail
Example
The report contained several factual inaccuracies.
El informe contenía varias inexactitudes.
C1 noun ɪnˈsɛpʃən

inception

inicio
Meaning
The establishment or starting point of an institution or activity.
Example
The inception of the company marked a new era in the industry.
La incepción de la empresa marcó una nueva era en la industria.
C1 noun /ɪnˈdaɪtmənt/

indictment

acusación formal
Meaning
a formal charge or accusation of a serious crime
Example
The indictment accused the company of multiple violations.
La acusación formal acusó a la empresa de múltiples violaciones.
C1 noun /ɪnˈdjuːsmənt/

inducement

inducido
Meaning
something that persuades or encourages someone to do something
Example
The company offered a bonus as an inducement to employees.
La empresa ofreció un bono como incentivo para los empleados.
C1 verb /ɪnˈfleɪt/

inflate

inflar
Meaning
to fill with air or gas so it expands; to increase excessively or artificially
Example
The mechanic inflated the tire to the correct pressure.
El mecánico infló el neumático a la presión correcta.
C1 adjective /ˈɪrɪtəbl/

irritable

irritable
Meaning
easily annoyed or made angry
Example
She became irritable after working long hours without rest.
Ella se volvió irritable después de trabajar muchas horas sin descanso.
C1 noun /ˌɪnflɛksɪˈbɪlɪti/

inflexibility

inflexibilidad
Meaning
the quality of being rigid or unwilling to change; lack of adaptability
Example
The inflexibility of the rules caused unnecessary delays.
La inflexibilidad de las reglas causó retrasos innecesarios.
C1 noun ˌɪrɪˈvɜːrsəbl ˈdæmɪdʒ

irreversible damage

daño irreversible
Meaning
Harm or injury that cannot be undone or repaired.
Example
Climate change causes irreversible damage to ecosystems.
El cambio climático causa daño irreversible a los ecosistemas.
C1 adjective /ɪnˈæk.tɪv/

Inactive

inactivo
Meaning
not active; not working; dormant; idle
Example
The volcano has been inactive for over a century.
El volcán ha estado inactivo durante más de un siglo.
C1 noun /ˈɪn.tə.lekt/

intellect

intelecto
Meaning
The ability to think, reason, and understand objectively.
Example
Her intellect is admired by all her colleagues.
Su intelecto es admirado por todos sus colegas.
C1 noun /ˌɪmɔːrˈtæləti/

immortality

inmortalidad
Meaning
the state of living forever; eternal life or lasting fame beyond death
Example
Many ancient cultures believed that heroes could achieve immortality through great deeds.
Muchas culturas antiguas creían que los héroes podían alcanzar la inmortalidad mediante grandes hazañas.
C1 adjective ˈɪn.lənd

Inland

del interior
Meaning
Situated in the interior of a country; away from the coast.
Example
Inland transport boosts local trade.
El transporte del interior impulsa el comercio local.
C1 adjective ˌɪm.pəˈsɛp.tɪ.bəl

imperceptible

imperceptible
Meaning
So subtle or gradual that it is difficult to notice or perceive
Example
The changes in his behavior were imperceptible at first.
Los cambios en su comportamiento eran imperceptibles al principio.
C1 verb ɪˈnɪʃɪeɪtɪd

initiated

iniciado
Meaning
Caused a process or action to begin; started something.
Example
The project was initiated to enhance marine biodiversity.
El proyecto fue iniciado para mejorar la biodiversidad marina.
C1 noun /ˈɪŋklɪŋ/

inkling

presentimiento
Meaning
A slight idea, hint, or suspicion about something.
Example
She had an inkling that he was planning a surprise.
Ella tenía una ligera sospecha de que él estaba planeando una sorpresa.
C1 adverb /ɪnˈvɜːrs.li/

Inversely

inversamente; en sentido opuesto
Meaning
in a way that is opposite or contrary; in reverse order or manner
Example
The price of goods is inversely related to their availability in the market.
El precio de los productos está inversamente relacionado con su disponibilidad en el mercado.
C1 noun /ˈaɪsətəʊp/

isotope

isótopo
Meaning
Atoms of the same element with equal number of protons but different numbers of neutrons.
Example
Carbon-14 is a radioactive isotope used in dating fossils.
El carbono-14 es un isótopo radiactivo utilizado en la datación de fósiles.
C1 adjective /ˌɪlɪˈdʒɪtɪmət/

illegitimate

ilegítimo
Meaning
Not authorized by law, rules, or standards; not recognized as valid.
Example
The court ruled the contract to be illegitimate.
El tribunal dictaminó que el contrato era ilegítimo.
C1 adjective ˌɪn.krəˈmen.təl

incremental

incremental
Meaning
Relating to or denoting an increase or addition, especially one of a series on a fixed scale; proceeding in small stages.
Example
Incremental changes ensure sustainability.
Los cambios incrementales aseguran la sostenibilidad.
C1 verb /ɪmˈpɛər/

impair

deteriorar
Meaning
to weaken or damage something, especially a function or ability
Example
Smoking can impair your lung capacity.
Fumar puede dañar tu capacidad pulmonar.
C1 adjective /ɪnˈtɜːrmənəbl/

interminable

interminable
Meaning
Seemingly endless; having no apparent end.
Example
The meeting felt interminable and exhausting.
La reunión parecía interminable y agotadora.
C1 adjective /ɪnˈvæljʊəbl/

invaluable

invaluable
Meaning
Extremely useful or indispensable.
Example
Her advice proved invaluable to my success.
Su consejo resultó invaluable para mi éxito.
C1 noun /ɪmˈpɛdɪmənt/

impediments

obstáculos
Meaning
A hindrance or obstruction in doing something; things that prevent progress or achievement.
Example
Economic impediments often hinder social development.
Los obstáculos económicos a menudo dificultan el desarrollo social.
C1 adjective /ɪnˈdʌktɪv/

inductive

inductivo
Meaning
characterized by the inference of general laws from particular instances; reasoning from specific cases to general principles
Example
The scientist used inductive reasoning to form a hypothesis.
El científico usó razonamiento inductivo para formular una hipótesis.
C1 adjective /ɪnˈstrʌktɪv/

instructive

instructivo
Meaning
useful and informative; providing knowledge or instruction
Example
The lecture was highly instructive and engaging.
La conferencia fue muy instructiva y atractiva.
C1 adjective /ɪnˈtændʒəbl/

intangible

intangible
Meaning
Unable to be touched or grasped; not having a physical presence.
Example
Trust is an intangible quality in relationships.
La confianza es una cualidad intangible en las relaciones.
C1 adjective /ɪnˈfriːkwənt/

infrequent

poco frecuente
Meaning
Happening rarely or not often.
Example
He made infrequent visits to his hometown after moving abroad.
Él hacía visitas poco frecuentes a su ciudad natal después de mudarse al extranjero.
C1 noun /ˈɪn.floʊ/

inflow

flujo
Meaning
The movement of things such as money, people, or water into a place.
Example
The inflow of tourists boosted the local economy.
El flujo de turistas impulsó la economía local.
C1 noun /ˈɪntrɪkəsi/

intricacy

complejidad
Meaning
the quality of being very detailed or complicated
Example
The intricacy of the design impressed everyone.
La complejidad del diseño impresionó a todos.
C1 adjective /ɪnˈtɛlɪdʒəbl/

intelligible

Meaning
Able to be understood; clear enough to be comprehended.
Example
Her speech was barely intelligible over the noise.
C1 adjective /ɪmˈpæʃənd/

impassioned

apasionado
Meaning
Filled with or showing great emotion.
Example
She gave an impassioned speech about human rights.
Ella dio un discurso apasionado sobre los derechos humanos.
C1 noun /ɪmˈpɒs.tər/

Impostor

impostor; fraude
Meaning
a person who pretends to be someone else in order to deceive others; a fraud
Example
The impostor convinced everyone he was a doctor until his fake credentials were discovered.
El impostor convenció a todos de que era un doctor hasta que se descubrió que sus credenciales eran falsas.
C1 adjective /ɪmˈpɜːrtɪnənt/

impertinent

impertinente
Meaning
rude and showing a lack of respect
Example
It was impertinent of him to question the manager's decision.
Fue impertinente de su parte cuestionar la decisión del gerente.
C1 adjective /ɪˈmækjələt/

immaculate

inmaculado
Meaning
perfectly clean, neat, or free from flaws
Example
Her room was immaculate, with everything in its place.
Su habitación estaba inmaculada, con todo en su lugar.
C1 noun /ɪnˈsɜːrdʒənt/

insurgent

insurgente
Meaning
A person who rises in revolt against authority or government.
Example
The army arrested several insurgents after the attack.
El ejército arrestó a varios insurgentes después del ataque.
C1 noun /ɪˈmiːdiəsi/

immediacy

inmediación, urgencia
Meaning
The quality of bringing one into direct and instant involvement with something, giving rise to a sense of urgency or excitement.
Example
The immediacy of digital communication has reshaped business operations.
La inmediatez de la comunicación digital ha transformado las operaciones comerciales.
C1 verb /ˈɪnsjuleɪt/

insulate

aislar
Meaning
To protect something by covering it, especially to prevent heat, sound, or electricity from escaping or entering.
Example
The house was insulated to reduce heating costs.
La casa fue aislada para reducir los costos de calefacción.
C1 adjective, noun /ˈɪnvəlɪd/ (adjective), /ɪnˈvælɪd/ (noun)

invalid

inválido
Meaning
Not valid; having no force or effect. Also refers to a person too weak or ill to care for themselves.
Example
The court declared the contract invalid.
El tribunal declaró el contrato inválido.
C1 noun /ɪmˌpɒsəˈbɪlɪti/

impossibility

imposibilidad
Meaning
the state or fact of being impossible; something that cannot be done or achieved
Example
Finishing the project in one day was an impossibility.
Terminar el proyecto en un día fue una imposibilidad.
C1 adjective /ɪmˈpɛtʃ.u.əs/

impetuous

impulsivo
Meaning
Acting or done quickly and without thought or care; impulsive.
Example
His impetuous decision led to unexpected consequences.
Su decisión impulsiva condujo a consecuencias inesperadas.
C1 verb /ˌɪnstɪˈtjuːʃənəlaɪz/

institutionalize

institucionalizar
Meaning
to establish something as a formal institution, custom, or practice
Example
The government seeks to institutionalize environmental protection.
El gobierno busca institucionalizar la protección ambiental.
C1 adjective /ɪnˈtræk.tə.bəl/

intractable

incontrolable
Meaning
Difficult or impossible to manage, control, or solve.
Example
The conflict has become an intractable problem.
El conflicto se ha convertido en un problema incontrolable.
C1 verb /ˌɪn.tɚˈtwaɪn/

intertwine

conectar o vincular de cerca; torcer o combinar estrechamente
Meaning
To connect or link closely; to twist together or combine closely.
Example
Their lives became intertwined through years of friendship.
Sus vidas se entrelazaron a lo largo de años de amistad.