Indefinite
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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 adjective /ˌɪnækˈsɛsəbl/

inaccessible

inaccesible
Meaning
unable to be reached, entered, or understood
Example
The remote village is almost inaccessible during the rainy season.
El pueblo remoto es casi inaccesible durante la temporada de lluvias.
C1 adjective /ˌɪntəˈrɑːɡətɪv/

interrogative

interrogativo
Meaning
Relating to or conveying a question; in grammar, used to form questions.
Example
She raised an interrogative eyebrow when she heard the news.
Ella levantó una ceja interrogativa cuando escuchó la noticia.
C1 noun /ˌaɪ.diˈɒl.ə.dʒi/

ideology

ideología
Meaning
A system of ideas and ideals, especially one that forms the basis of economic or political theory and policy.
Example
Democracy is based on the ideology of freedom and equality.
La democracia se basa en la ideología de la libertad y la igualdad.
C1 verb ɪˈmɜːrs

immerse

sumergir
Meaning
To involve oneself deeply in a particular activity or interest; to surround completely.
Example
Immerse yourself in the new language.
Sumérgete en el nuevo idioma.
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 noun /ˌɪntərˈmɪʃən/

intermission

intermedio
Meaning
A pause or break, especially during a performance or event.
Example
The play had a twenty-minute intermission.
La obra tuvo un intermedio de veinte minutos.
C1 noun ˈɪm.pɪ.təs

impetus

impulso
Meaning
The force or motivation that drives something forward; momentum.
Example
The new policy provided an impetus for economic growth.
La nueva política proporcionó un impulso para el crecimiento económico.
C1 verb /ˌɪn.trəˈspekt/

introspect

introspectar
Meaning
To examine one's own thoughts, feelings, or mental state.
Example
He often introspects before making important decisions.
Él a menudo se introspecta antes de tomar decisiones importantes.
C1 noun /ɪnˈfɜːməri/

infirmary

hospital
Meaning
A hospital or place where the sick or injured are cared for.
Example
The school had an infirmary for minor injuries.
La escuela tenía un hospital para lesiones menores.
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 /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/verb /ˈɪmprɪnt/

imprint

huella
Meaning
A mark or impression made by pressure; to establish or fix firmly in someone's mind.
Example
The event left an indelible imprint on the city's history.
El evento dejó una huella indeleble en la historia de la ciudad.
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 noun ɪnˌten.sɪ.fɪˈkeɪ.ʃən

intensification

intensificación
Meaning
The process of becoming or making something more intense or extreme.
Example
The intensification of climate change requires urgent action.
La intensificación del cambio climático requiere una acción urgente.
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 adjective /ˌɪndɪˈsaɪsɪv/

Indecisive

indeciso
Meaning
unable to make decisions quickly; hesitant; wavering
Example
She was indecisive about which university to attend.
Ella estaba indecisa sobre qué universidad asistir.
C1 adjective /ˈɜːrksəm/

irksome

molesto
Meaning
annoying or irritating
Example
Waiting in a long line is one of the most irksome tasks.
Esperar en una larga fila es una de las tareas más molestas.
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 verb /ˌɪntərˈsɛpt/

intercept

interceptar
Meaning
to stop, catch, or seize something on its way from one place to another
Example
The police intercepted the stolen car before it crossed the border.
La policía interceptó el coche robado antes de que cruzara la frontera.
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 noun /ɪnˈhɛrɪtər/

inheritor

heredero
Meaning
a person who receives money, property, or a title when someone dies
Example
She became the inheritor of her family's estate.
Ella se convirtió en la heredera de la propiedad de su familia.
C1 adjective /ɪnˈtɛlɪdʒəbl/

intelligible

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

infiltrate

infiltrarse
Meaning
to secretly enter or gain access to a place or group
Example
The spies managed to infiltrate the enemy base.
Los espías lograron infiltrarse en la base enemiga.
C1 adjective /ɪˈluː.sɪv/

Illusive

ilusorio; que parece existir pero no es real; engañoso
Meaning
deceptive; appearing to exist but not real; misleading
Example
The promise of easy money proved to be illusive and misleading.
La promesa de dinero fácil resultó ser ilusoria y engañosa.
C1 verb /ɪnˈvɪɡ.ər.eɪt/

invigorate

revitalizar
Meaning
To give strength or energy to someone or something.
Example
A morning walk can invigorate both body and mind.
Una caminata matutina puede revitalizar tanto el cuerpo como la mente.
C1 adjective /ˌɪndɪˈstrʌktəbl/

indestructible

indestructible
Meaning
Impossible to destroy or break.
Example
The superhero's shield was said to be indestructible.
Se dijo que el escudo del superhéroe era indestructible.
C1 adjective /ɪnˈkɒŋɡruəs/

incongruous

incongruente
Meaning
Not fitting in with or suitable for the surroundings.
Example
His jokes were incongruous during the serious meeting.
Sus chistes fueron incongruentes durante la reunión seria.
C1 noun /ˌɪnsɪɡˈnɪfɪkəns/

insignificance

insignificancia
Meaning
The quality of being unimportant or trivial.
Example
He felt a sense of insignificance in the vast universe.
Él sintió un sentido de insignificancia en el vasto universo.
C1 verb /ˈɪrɪˌɡeɪt/

irrigate

regar
Meaning
to supply water to land or crops; to wash out a wound with water
Example
Farmers irrigate their fields during dry seasons.
Los agricultores riegan sus campos durante la temporada seca.
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 noun /ˈɪnflʌks/

influx

afluencia
Meaning
A large arrival or flow of people or things.
Example
The city experienced an influx of tourists during the festival.
La ciudad experimentó una afluencia de turistas durante el festival.
C1 noun /ˈɪn.fən.tri/

Infantry

infantería
Meaning
soldiers marching or fighting on foot; foot soldiers collectively
Example
The infantry advanced across the battlefield on foot.
La infantería avanzó a través del campo de batalla a pie.
C1 adjective /ɪmˈpɜːrviəs/

impervious

impermeable
Meaning
Not allowing fluid to pass through; unable to be affected by something.
Example
The jacket is impervious to rain.
La chaqueta es impermeable a la lluvia.
C1 adjective /ɪnˈveə.ri.ə.bəl/

Invariable

invariable; constante; siempre igual
Meaning
never changing; constant; always the same
Example
His invariable routine includes morning exercise and coffee.
Su rutina invariable incluye ejercicio por la mañana y café.
C1 verb /ɪnˈstɪl/

instill

instruir
Meaning
to gradually but firmly establish an idea, attitude, or habit in someone's mind
Example
Parents try to instill good values in their children.
Los padres intentan inculcar buenos valores en sus hijos.
C1 adverb, adjective /ˌɪnkɑːɡˈniːtoʊ/

incognito

incógnito
Meaning
In disguise or with one's identity concealed.
Example
The celebrity traveled incognito to avoid the paparazzi.
La celebridad viajó incognito para evitar a los paparazzi.
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 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 adjective /ˌaɪdiəˈlɪstɪk/

Idealistic

idealista
Meaning
pursuing high principles or ideals; unrealistically optimistic
Example
She has an idealistic view of changing the world.
Ella tiene una visión idealista de cambiar el mundo.
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 /ˌɪnkɑːrˈneɪʃən/

incarnation

encarnación
Meaning
the embodiment of a deity, spirit, or quality in a physical form
Example
The monk was considered the incarnation of compassion.
El monje fue considerado la encarnación de la compasión.
C1 noun /ɪˈnɜː.ʃə/

Inertia

inercia; falta de actividad
Meaning
a tendency to do nothing or remain unchanged; lack of activity or movement
Example
The team's inertia prevented them from adapting to the rapidly changing market conditions.
La inercia del equipo les impidió adaptarse a las condiciones de mercado en rápido cambio.
C1 adjective /ˌɪməˈtɪəriəl/

immaterial

inmaterial
Meaning
Not important or relevant; lacking physical substance.
Example
The judge ruled that the argument was immaterial to the case.
El juez falló que el argumento no era relevante para el caso.
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 /ɪnˈdɪɡ.nə.ti/

Indignity

indignidad; humillación; deshonra;
Meaning
treatment or circumstances that cause one to feel shame or loss of dignity; humiliation
Example
She refused to suffer the indignity of being searched without proper cause.
Ella se negó a sufrir la indignidad de ser registrada sin causa justificada.
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 /ˌɪn.səbˈstæn.ʃəl/

insubstantial

insustancial
Meaning
Lacking strength, substance, or solidity.
Example
The evidence provided was insubstantial and unconvincing.
La evidencia proporcionada fue insustancial y poco convincente.
C1 adjective /ɪˈnɒkjuəs/

innocuous

inofensivo
Meaning
Not harmful or offensive.
Example
His remark was completely innocuous and not meant to offend anyone.
Su comentario fue completamente inofensivo y no tenía la intención de ofender a nadie.
C1 noun /ɪnˈdɪf.ər.əns/

Indifference

indiferencia; desinterés; apatía
Meaning
lack of interest, concern, or sympathy; the state of not caring about something
Example
His indifference to his studies resulted in poor grades throughout the semester.
Su indiferencia por sus estudios resultó en malas calificaciones durante todo el semestre.
C1 verb /ɪnˈdaɪt/

indict

acusar
Meaning
to formally accuse someone of committing a serious crime
Example
The grand jury decided to indict the politician for corruption.
El gran jurado decidió acusar al político por corrupción.
C1 noun /ˌɪntɪˈmeɪʃən/

intimation

insinuación
Meaning
A subtle or indirect hint or suggestion.
Example
She gave no intimation of her plans.
Ella no dio ninguna insinuación sobre sus planes.
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 noun /ɪnˈsɜːrdʒəns/

insurgence

insurgencia
Meaning
An act of rebellion or uprising against authority.
Example
The government struggled to contain the growing insurgence.
El gobierno luchó por contener la creciente insurgencia.
C1 adjective /ɪˈlɪsɪt/

illicit

ilícito
Meaning
Forbidden by law, rules, or custom.
Example
The police shut down the illicit drug operation.
La policía cerró la operación de drogas ilícitas.
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 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 adjective, noun /ɪnˈdɪkətɪv/

indicative

indicativo
Meaning
Serving as a sign or expression of something; in grammar, a mood used to make factual statements.
Example
His tone was indicative of his frustration.
Su tono era indicativo de su frustración.
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 /ɪnˈfæləbl̩/

infallible

infalible
Meaning
incapable of making mistakes or being wrong
Example
Her judgment seemed infallible in matters of finance.
Su juicio parecía infalible en cuestiones financieras.
C1 adjective /ˌɪn.səˈbɔːr.dɪ.nət/

insubordinate

insubordinado
Meaning
Defiant of authority; disobedient to orders.
Example
The insubordinate employee refused to follow the manager's instructions.
El empleado insubordinado se negó a seguir las instrucciones del gerente.
C1 noun /ɪnˈsaɪtmənt/

incitement

incitación
Meaning
the action of provoking unlawful or violent behavior
Example
He was arrested for incitement to riot.
Fue arrestado por incitación a la violencia.
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 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 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 /ɪnˈkɜːrʒən/

incursion

incursión
Meaning
A sudden attack or invasion into a place or territory.
Example
The army repelled the enemy incursion at the border.
El ejército repelió la incursión enemiga en la frontera.
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 noun /ˈɪd.i.əm/

idiom

modismo
Meaning
A group of words whose meaning is different from the meanings of the individual words.
Example
The idiom 'break the ice' means to start a conversation in a friendly way.
El modismo 'romper el hielo' significa comenzar una conversación de manera amistosa.
C1 adjective /ɪmˈpjʊər/

Impure

impuro
Meaning
contaminated; not clean; mixed with foreign substances
Example
The impure water caused health problems in the village.
El agua impura causó problemas de salud en el pueblo.
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 noun /ˈɪnsɪdəns/

incidence

incidencia
Meaning
the occurrence, rate, or frequency of something
Example
The incidence of road accidents has decreased this year.
La incidencia de accidentes de tráfico ha disminuido este año.
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 adjective /ɪnˈdetɪd/

Indebted

endeudado; agradecido
Meaning
owing money or gratitude to someone; obligated; grateful
Example
I am deeply indebted to my teacher for all her guidance.
Estoy profundamente endeudado con mi profesora por toda su orientación.
C1 verb /ɪnˈvoʊk/

invoke

invocar
Meaning
to call upon a higher power, authority, or principle for help, support, or justification
Example
The lawyer invoked the constitution to defend his client.
El abogado invocó la constitución para defender a su cliente.
C1 noun /aɪl/

isle

pequeña isla
Meaning
A small island or peninsula, often poetic or literary.
Example
They spent their honeymoon on a beautiful tropical isle.
Pasaron su luna de miel en una hermosa isla tropical.
C1 noun ˌɪn.tuˈɪʃ.ən

intuition

intuición
Meaning
The ability to understand something immediately, without the need for conscious reasoning.
Example
Her intuition told her something was wrong.
Su intuición le dijo que algo estaba mal.
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 /ˌɪn.ɪˈfɛk.tʃu.əl/

ineffectual

ineficaz
Meaning
Not producing any or the desired effect; lacking the ability or qualities to achieve a purpose.
Example
The manager’s ineffectual leadership caused the team to lose motivation.
El liderazgo ineficaz del gerente hizo que el equipo perdiera la motivación.
C1 adjective ˌɪn.təˈdɪs.ɪ.plɪ.nər.i

interdisciplinary

interdisciplinario
Meaning
Relating to more than one branch of knowledge.
Example
The interdisciplinary approach in education enhances problem-solving skills.
El enfoque interdisciplinario en la educación mejora las habilidades para resolver problemas.
C1 adjective /ˈɪmpjəd(ə)nt/

impudent

descarado, insolente
Meaning
not showing due respect for another person; rude
Example
The impudent child talked back to the teacher.
El niño descarado le contestó al maestro.
C1 noun /ɪmˈbæl.əns/

Imbalance

desequilibrio
Meaning
lack of proportion or relation between corresponding things; unequal distribution
Example
The doctor said the patient's dizziness was caused by an inner ear imbalance.
El doctor dijo que el mareo del paciente fue causado por un desequilibrio en el oído interno.
C1 adjective /ˈɪmpətənt/

impotent

impotente
Meaning
Lacking power, ability, or strength to take effective action.
Example
The citizens felt impotent against the corrupt system.
Los ciudadanos se sintieron impotentes contra el sistema corrupto.
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 adjective /ˌɪnˌkɒnsɪˈkwɛnʃəl/

inconsequential

insignificante
Meaning
Not important or significant; too small to matter.
Example
The mistake was minor and inconsequential.
El error fue menor e insignificante.
C1 noun /ɪnˈdem.nə.ti/

Indemnity

indemnización
Meaning
security or protection against a loss or other financial burden; compensation for damage or loss
Example
The insurance company provided full indemnity for the damages caused by the flood.
La compañía de seguros proporcionó indemnización completa por los daños causados por la inundación.
C1 noun /ˈɪntərˌluːd/

interlude

interludio
Meaning
A short period of time that comes between two events; an interval.
Example
There was a brief musical interlude between the two acts of the play.
Hubo un breve interludio musical entre los dos actos de la obra.
C1 noun /ˌɪnfɪˈdɛləti/

infidelity

infidelidad
Meaning
the act of being unfaithful to a spouse or partner
Example
Their marriage ended due to his infidelity.
Su matrimonio terminó debido a su infidelidad.
C1 adjective /ɪnˈtjuː.ɪ.tɪv/

intuitive

intuitivo
Meaning
Based on instinctive understanding rather than reasoning.
Example
The software has an intuitive design that makes it easy to use.
El software tiene un diseño intuitivo que lo hace fácil de usar.
C1 adjective /ˌɪnəˈtɛntɪv/

inattentive

inattento
Meaning
not paying attention; lacking focus or concentration
Example
The inattentive student missed several important instructions.
El estudiante inattento perdió varias instrucciones importantes.
C1 adjective /ɪnˈhɪbɪtɪd/

inhibited

inhibido
Meaning
Unable to act in a relaxed and natural way, especially due to self-consciousness or restraint.
Example
He was too inhibited to express his true feelings.
Él estaba demasiado inhibido para expresar sus verdaderos sentimientos.
C1 adjective /ˈɪnsələnt/

insolent

insolente, arrogante
Meaning
showing a rude and arrogant lack of respect
Example
The insolent student refused to follow the teacher's instructions.
El estudiante insolente se negó a seguir las instrucciones del maestro.
C1 adjective /ɪnˈhɛrənt/

inherent

inherente
Meaning
Existing in something as a natural, permanent, or essential quality.
Example
There are inherent risks in extreme sports.
Existen riesgos inherentes en los deportes extremos.
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 adjective /ˌɪndɪˈvɪzəbl/

indivisible

indivisible
Meaning
Not able to be divided or separated.
Example
The country's unity was indivisible despite differences.
La unidad del país era indivisible a pesar de las diferencias.
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 noun /ˈɪnstɪˌɡeɪtər/

instigator

instigador
Meaning
A person who brings about or initiates something, usually something bad.
Example
The police identified him as the instigator of the violence.
La policía lo identificó como el instigador de la violencia.
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 noun ˌɪndɪˈspensəbl səˈpɔːrt

indispensable support

apoyo indispensable
Meaning
Essential assistance that cannot be done without; absolutely necessary help.
Example
Volunteers provide indispensable support to communities.
Los voluntarios proporcionan apoyo indispensable a las comunidades.
C1 noun /ˌɪnkənˈsɪstənsi/

inconsistency

inconsistencia
Meaning
The quality of being contradictory, irregular, or not staying the same.
Example
There is an inconsistency between his words and actions.
Hay una inconsistencia entre sus palabras y acciones.
C1 adjective /ɪmˈpʌlsɪv/

impulsive

impulsivo, de impulso
Meaning
acting suddenly without careful thought
Example
She made an impulsive decision to buy the car.
Tomó una decisión impulsiva de comprar el coche.
C1 noun /ɪnˈfɜːrnoʊ/

inferno

incendio
Meaning
a large, intense fire that is dangerously out of control
Example
The building turned into an inferno within minutes.
El edificio se convirtió en un incendio en minutos.
C1 noun ˌɪnfrəˈstrʌktʃərəl dɪˈveləpmənt

infrastructural development

desarrollo infraestructural
Meaning
The process of building and improving the basic physical and organizational structures and facilities needed for the operation of a society or enterprise.
Example
Infrastructural development is necessary for efficient recycling.
El desarrollo infraestructural es necesario para el reciclaje eficiente.
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 noun /ˈɪm.pæs/

impasse

impasse
Meaning
A situation where no progress is possible.
Example
The negotiations reached an impasse, delaying the agreement.
Las negociaciones llegaron a un impasse, retrasando el acuerdo.
C1 adjective /ɪnˈhjuːmən/

Inhuman

inhumano
Meaning
lacking human qualities; cruel; brutal; savage
Example
The dictator's inhuman treatment of prisoners shocked the international community.
El trato inhumano del dictador hacia los prisioneros sorprendió a la comunidad internacional.
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 /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 /ɪnˈsɒlvənt/

insolvent

insolvente
Meaning
unable to pay debts owed
Example
The insolvent firm could not meet its financial obligations.
La empresa insolvente no pudo cumplir con sus obligaciones financieras.
C1 verb /ˈɪnkjʊˌbeɪt/

incubate

incubar
Meaning
to keep eggs, cells, or organisms at the right conditions for development
Example
The hen will incubate the eggs until they hatch.
La gallina incubará los huevos hasta que eclosionen.
C1 adjective /ɪnˈtrɛpɪd/

intrepid

intrépido
Meaning
fearless and adventurous, often used humorously
Example
The intrepid traveler explored the jungle alone.
El intrépido viajero exploró la jungla solo.
C1 noun ˌɪn.ɪˈfɪʃ.ən.si

inefficiency

ineficiencia
Meaning
The state or quality of not achieving maximum productivity; failure to make the best use of time or resources.
Example
Government inefficiency leads to slow project completion.
La ineficiencia del gobierno conduce a una finalización lenta del proyecto.
C1 adjective /ɪnˈseɪʃəbl̩/

insatiable

insaciable
Meaning
impossible to satisfy; always wanting more
Example
Her insatiable curiosity drove her to read every book in the library.
Su insaciable curiosidad la llevó a leer todos los libros de la biblioteca.
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 ɪˌræʃ.ənˈæl.ɪ.ti

irrationality

irracionalidad, falta de lógica, irrazonabilidad
Meaning
The quality of being illogical or unreasonable; lack of rational thought.
Example
His decision was driven by complete irrationality.
Su decisión fue impulsada por una irracionalidad completa.
C1 noun /ɪˌreɡjəˈlærɪti/

irregularity

irregularidad
Meaning
lack of regularity or consistency; a deviation from what is normal, expected, or orderly
Example
The audit revealed several financial irregularities in the company’s records.
La auditoría reveló varias irregularidades financieras en los registros de la empresa.
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 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 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 adjective /ˌɪndɪˈskriːt/

indiscreet

imprudente
Meaning
Not careful in what one says or does, likely to reveal secrets or offend.
Example
It was indiscreet of him to mention the plan in public.
Fue imprudente de su parte mencionar el plan en público.
C1 adjective ˌɪn.təˈmɪt.ənt

intermittent

intermitente
Meaning
Happening irregularly, not continuously.
Example
The rain was intermittent throughout the day.
La lluvia fue intermitente durante todo el día.
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.