orchestrated
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C1 verb ˈɔː.kɪ.streɪ.tɪd

orchestrated

orquestado
Meaning
Planned or coordinated carefully and deliberately.
Example
The attacks were orchestrated with precision.
Los ataques fueron orquestados con precisión.
C1 noun /ˈaʊtriːtʃ/

outreach

expansión de la asistencia
Meaning
The act of providing services or support to people who might not otherwise have access to them.
Example
The charity launched a new outreach program for the homeless.
La caridad lanzó un nuevo programa de expansión de la asistencia para las personas sin hogar.
C2 adjective /əbˈstrɛpərəs/

obstreperous

ruidoso y difícil de controlar
Meaning
Noisy and difficult to control.
Example
The obstreperous students disrupted the class.
Los estudiantes ruidosos interrumpieron la clase.
C2 adjective /ˈoʊ.pən ˈhɑrt.ɪd/

Open-hearted

de corazón abierto; generoso y sincero; cálidamente receptivo;
Meaning
Kind and generous; sincere and honest; warmly receptive;
Example
She welcomed the strangers with an open-hearted smile and invited them for dinner.
Ella dio la bienvenida a los extraños con una sonrisa de corazón abierto e invitó a cenar.
B2 noun /əˈfɛns/

offense

delito
Meaning
an illegal act; a crime
Example
The offense was committed in broad daylight.
El delito fue cometido a plena luz del día.
B2 noun /ɔːrˈɡæn.ɪk ˈfɑːr.mɪŋ/

organic farming

agricultura orgánica
Meaning
Farming method that avoids synthetic chemicals and fertilizers, using natural methods instead.
Example
Organic farming improves soil health and reduces pollution.
La agricultura orgánica mejora la salud del suelo y reduce la contaminación.
B1 adverb /əˈrɪdʒɪnəli/

originally

originalmente
Meaning
in the beginning, at first
Example
Originally, she wanted to be a doctor.
Originalmente, ella quería ser doctora.
A2 noun /ˈoʊ.nər/

Owner

dueño
Meaning
a person who owns something; someone who has legal possession of property
Example
The owner of the restaurant greeted us warmly.
El dueño del restaurante nos saludó calurosamente.
B2 noun/verb /ˌoʊvərˈlæp/

overlap

solapamiento
Meaning
To extend over and cover partly; an area where things coincide.
Example
The two meetings overlap by an hour.
Las dos reuniones se solapan por una hora.
B1 noun ˌɔː.ɡən.aɪˈzeɪ.ʃən

organization

organización
Meaning
An organized group of people with a particular purpose, such as a business or government department.
Example
The organization was officially inaugurated in 2024.
La organización fue inaugurada oficialmente en 2024.
C1 adjective /əˈbliːk/

Oblique

oblicuo; diagonal; indirecto o evasivo
Meaning
slanting; diagonal; indirect or evasive
Example
The artist drew an oblique line across the canvas.
El artista dibujó una línea oblicua en el lienzo.
C2 noun /ˈəʊpəs/

opus

obra creativa
Meaning
A creative work, especially a large and important piece of music or art.
Example
The composer considered the symphony his greatest opus.
El compositor consideró la sinfonía su mayor obra creativa.
B1 noun /ˈɑː.lɪv/

Olive

aceituna
Meaning
a small oval fruit with a hard pit, typically green or black, used for eating or making oil
Example
Olive oil is considered one of the healthiest cooking oils available.
El aceite de oliva se considera uno de los aceites de cocina más saludables disponibles.
B1 noun /ˈɔr.ə.ʒɪn/

Origin

origen
Meaning
the point or place where something begins, arises, or is derived; the source
Example
Scientists are studying the origin of the universe.
Los científicos están estudiando el origen del universo.
B1 verb /oʊ/

owe

deber
Meaning
to be under obligation to pay or repay; to be indebted
Example
I owe my success to my parents' support.
Le debo mi éxito al apoyo de mis padres.
C2 noun /əbˈsɪdiən/

obsidian

obsidiana (roca volcánica oscura y vidriosa)
Meaning
A hard, dark, glasslike volcanic rock formed by rapid solidification of lava.
Example
The knife was made from sharp obsidian.
El cuchillo estaba hecho de obsidiana afilada.
C2 noun ˈoʊʃən ˌstrætɪfɪˈkeɪʃən

ocean stratification

estratificación oceánica
Meaning
The formation of layers in ocean water due to differences in density.
Example
Ocean stratification affects marine biodiversity.
La estratificación oceánica afecta la biodiversidad marina.
B2 noun /ˌɒb.zəˈveɪ.ʃənz/

observations

observación
Meaning
The action or process of observing something carefully.
Example
Observations of distant galaxies provide new insights.
Las observaciones de galaxias distantes proporcionan nuevas ideas.
C2 noun /ˈɔːrdnəns/

ordnance

suministros militares
Meaning
Military supplies including weapons, ammunition, and combat equipment.
Example
The army stored ordnance in a secure facility outside the city.
El ejército almacenó suministros militares en una instalación segura fuera de la ciudad.
B2 noun /oʊˈbiː.di.əns/

Obedience

obediencia
Meaning
compliance with an order, request, or law; submission to authority
Example
Children should show obedience to their parents.
Los niños deben mostrar obediencia a sus padres.
B2 noun /ɑːks/

Ox

buey
Meaning
a large strong animal used for pulling heavy loads or plowing fields
Example
The farmer used an ox to plow the field.
El agricultor usó un buey para arar el campo.
B2 noun /ˈoʊ.dər/

Odour

olor
Meaning
a distinctive smell, especially an unpleasant one
Example
The odour of fresh bread filled the kitchen.
El olor de pan fresco llenó la cocina.
B2 verb /ɒpt/

opt

elegir
Meaning
to choose or decide to do something instead of something else
Example
Many students opt to study abroad for better opportunities.
Muchos estudiantes optan por estudiar en el extranjero para tener mejores oportunidades.
C1 noun ɔːrˈdiːl

ordeal

prueba difícil
Meaning
A physical or mental painful experience that must be endured
Example
Surviving the wilderness was a tough ordeal for them.
Sobrevivir en la naturaleza fue una dura prueba para ellos.
A2 adjective/adverb /ˈɒnˌlaɪn/

online

en línea
Meaning
connected to or available through the internet
Example
I prefer shopping online rather than going to stores.
Prefiero comprar en línea en lugar de ir a las tiendas.
B2 noun /ˈaʊt.kʌm/

Outcome

resultado; consecuencia;
Meaning
the result or consequence of an action or situation; the final product
Example
The outcome of the election surprised everyone.
El resultado de las elecciones sorprendió a todos.
C1 noun /ˈoʊvərˌsiːər/

overseer

supervisor
Meaning
a person who supervises work or workers; a manager
Example
The overseer made sure the workers followed safety rules.
El supervisor se aseguró de que los trabajadores siguieran las reglas de seguridad.
C2 noun /oʊliˈændər/

Oleander

oleandro
Meaning
a poisonous evergreen shrub with clusters of white, pink, or red flowers
Example
The beautiful oleander flowers bloomed in the garden despite their toxic nature.
Las hermosas flores de oleandro florecieron en el jardín a pesar de su naturaleza tóxica.
B2 adjective /aʊtˈreɪdʒəs/

outrageous

atroz
Meaning
Shockingly bad or excessive; very unusual or amusing.
Example
The comedian told an outrageous joke.
El comediante contó un chiste atroz.
C1 verb /əˈprɛs/

oppress

oprimir
Meaning
to keep someone down by harsh and unfair use of authority; to suppress
Example
The dictator oppressed the people for decades.
El dictador oprimió a la gente durante décadas.
B1 verb /əˈkɜːr/

occur

ocurrir
Meaning
to happen or take place; to be found or present
Example
The accident occurred at the intersection during rush hour.
El accidente ocurrió en la intersección durante la hora punta.
B1 verb /ˈɒpəreɪt/

operate

operar
Meaning
to function; to control or manage; to perform surgery
Example
The surgeon will operate on the patient tomorrow.
El cirujano operará al paciente mañana.
C2 adjective /ˈɔːrnəri/

ornery

gruñón
Meaning
bad-tempered and combative; stubborn
Example
The ornery old man refused to leave his chair.
El gruñón anciano se negó a dejar su silla.
C1 noun /ˌɑːk.sɪˈmɔːr.ɒn/

oxymoron

oxímoron
Meaning
a figure of speech where two contradictory terms are combined
Example
The phrase 'deafening silence' is a classic oxymoron.
La frase 'silencio ensordecedor' es un oxímoron clásico.
B2 verb /əˈblaɪdʒ/

oblige

obligar
Meaning
to compel or require someone to do something; to help or do a favor
Example
I would be happy to oblige you with the information you need.
Estaría feliz de obligarte con la información que necesitas.
C1 noun /ˈoʊ.mən/

Omen

presagio de buena o mala suerte futura
Meaning
an event regarded as a sign of future good or bad luck
Example
Many people consider a black cat crossing your path a bad omen.
Muchas personas consideran que un gato negro cruzando tu camino es un mal presagio.
C1 adjective /ˌoʊvərˈbɛrɪŋ/

overbearing

opresivo
Meaning
unpleasantly or arrogantly domineering
Example
His overbearing attitude made everyone uncomfortable.
Su actitud opresiva hizo que todos se sintieran incómodos.
A2 noun /ˈʌv.ən/

Oven

horno
Meaning
an enclosed compartment used for heating, baking, or drying food
Example
She baked cookies in the oven for thirty minutes.
Ella horneó galletas en el horno durante treinta minutos.
B2 noun /ˈɒkjʊpənt/

occupant

ocupante
Meaning
A person who resides in or is present in a house, vehicle, seat, or place.
Example
The car had three occupants at the time of the accident.
El coche tenía tres ocupantes en el momento del accidente.
C1 noun /ɒpˈtɒmətri/

optometry

optometría
Meaning
The practice or profession of examining the eyes and prescribing corrective lenses.
Example
She studied optometry at the university to become an eye specialist.
Estudió optometría en la universidad para convertirse en especialista en ojos.
C1 noun əˈblɪv.i.ən

oblivion

olvido, destrucción, desaparición
Meaning
The state of being unaware or unconscious of what is happening; complete forgetfulness.
Example
His name faded into oblivion over time.
Su nombre se desvaneció en el olvido con el tiempo.
A2 noun /ɔɪl/

Oil

aceite
Meaning
a viscous liquid derived from petroleum or plants, used for cooking or fuel
Example
Heat the oil in a pan before adding the vegetables.
Calienta el aceite en una sartén antes de añadir las verduras.
C1 noun /ˈɔːr.ə.tɔːr.i/

oratory

oratoria
Meaning
The art of public speaking; skilled and confident delivery of speeches to an audience.
Example
His exceptional oratory skills won him the debate competition.
Sus excepcionales habilidades oratorias le ganaron la competencia de debate.
C2 adjective /ˌɒbsəˈlɛsnt/

obsolescent

obsoleto
Meaning
Becoming outdated or on the way to becoming obsolete.
Example
The obsolescent technology could not compete with modern devices.
La tecnología obsoleta no pudo competir con los dispositivos modernos.
A1 adjective /ˈʌðər/

other

otro
Meaning
used to refer to something different from the one already mentioned or known
Example
I don't want this one, I will take the other one.
No quiero este, tomaré el otro.
C1 noun /ˈɔːrdɪnəns/

ordinance

ordenanza
Meaning
An authoritative rule, law, or decree issued by a city, town, or authority.
Example
The city council passed an ordinance banning smoking in public parks.
El consejo municipal aprobó una ordenanza que prohíbe fumar en los parques públicos.
B2 noun ˈoʊzoʊn dɪˈpliʃən

ozone depletion

depleción de ozono
Meaning
The reduction in the amount of ozone in the Earth's stratosphere, leading to increased UV radiation.
Example
Ozone depletion increases UV radiation.
La depleción de ozono aumenta la radiación UV.
C2 adjective /əbˈsiːkwɪəs/

obsequious

servil
Meaning
Excessively obedient or attentive in a servile way.
Example
The waiter gave an obsequious bow to every customer.
El camarero hizo una reverencia servil a cada cliente.
B1 adverb /ˈʌðərwaɪz/

Otherwise

de otra manera; si no; o sino
Meaning
in a different way; if not; or else; apart from that
Example
Study hard, otherwise you will fail the exam.
Estudia mucho, de lo contrario, reprobarás el examen.
C1 noun /ˈɑn.set/

Onset

inicio; comienzo
Meaning
the beginning or early stages of something; the start of a medical condition
Example
The onset of winter brought heavy snowfall.
El inicio del invierno trajo fuertes nevadas.
C2 noun /ˌɔːrnɪˈθɒlədʒɪst/

ornithologist

ornitólogo
Meaning
a scientist who studies birds
Example
The ornithologist spent years studying migratory birds.
El ornitólogo pasó años estudiando aves migratorias.
C1 adjective əʊˈpeɪk

opaque

opaco, impenetrable, difícil de entender
Meaning
Not able to be seen through; not transparent; difficult to understand.
Example
The glass was too opaque to see through.
El vidrio era tan opaco que no se podía ver a través de él.
C2 adjective /ɑːlˈfæktəri/

olfactory

olfatorio
Meaning
Relating to the sense of smell.
Example
The perfume activated her olfactory nerves immediately.
The perfume activated her olfactory nerves immediately.
C1 noun /ˌɑːpərˈtuːnɪst/

opportunist

oportunista
Meaning
A person who takes advantage of situations for personal gain, often disregarding principles.
Example
He is seen as an opportunist who always puts his interests first.
Se le ve como un oportunista que siempre pone sus intereses primero.
B2 noun /ˈaʊtˌfɪt/

outfit

conjunto de ropa
Meaning
A set of clothes worn together, often for a particular occasion.
Example
She wore a beautiful outfit to the party.
Ella usó un hermoso conjunto de ropa para la fiesta.
C1 adjective /ˌɔːrθəˈpiːdɪk/

orthopedic

relacionado con la corrección de deformidades óseas o musculares
Meaning
Relating to the correction of deformities of bones or muscles.
Example
She visited an orthopedic surgeon for her back pain.
Ella visitó a un cirujano ortopédico por el dolor en la espalda.
C1 noun /ˈaʊtpoʊst/

outpost

puesto avanzado
Meaning
A small military camp or position at some distance from the main force, used especially as a guard.
Example
The soldiers were stationed at a remote outpost.
Los soldados fueron apostados en un puesto avanzado remoto.
B1 noun /ˈɒbstəkəlz/

obstacles

obstáculos
Meaning
Things that block one's way or prevent or hinder progress.
Example
Obstacles in life can often lead to valuable lessons.
Los obstáculos en la vida a menudo conducen a lecciones valiosas.
B1 adjective /ˌoʊvərˈsiːz/

overseas

en el extranjero
Meaning
in or to a foreign country across the sea
Example
He went overseas for higher education.
Él fue al extranjero para estudiar.
B2 noun /ˈɔr.fən.ɪʒ/

Orphanage

orfanato
Meaning
an institution for the care and education of children who have lost their parents
Example
The charity built a new orphanage for homeless children.
La caridad construyó un nuevo orfanato para niños sin hogar.
C1 adjective /oʊˈbiːs/

obese

obeso
Meaning
Extremely overweight; having an excessive amount of body fat.
Example
The doctor advised the obese patient to adopt a healthier lifestyle.
El doctor le recomendó al paciente obeso adoptar un estilo de vida más saludable.
B2 noun ˈɔː.bɪt

orbit

órbita
Meaning
The curved path of a celestial object around a star, planet, or moon.
Example
The satellite maintains its orbit around Earth.
El satélite mantiene su órbita alrededor de la Tierra.
C2 noun /ˈaʊtˌrɪɡər/

outrigger

estructura de refuerzo
Meaning
a projecting structure on a boat, used for stability, or a boat fitted with such support
Example
The fisherman paddled his outrigger canoe across the lagoon.
El pescador remó su canoa con outtrigger a través de la laguna.
B2 noun /ˈoʊtˌmiːl/

oatmeal

avena cocida
Meaning
A type of porridge made from ground oats, often eaten for breakfast.
Example
She eats a bowl of oatmeal every morning for breakfast.
Ella come un tazón de avena cocida todas las mañanas para el desayuno.
B2 verb /ˈɒkjʊpaɪ/

occupy

ocupar
Meaning
to take up space or time; to live or work in a place
Example
The new family will occupy the house next month.
La nueva familia ocupará la casa el próximo mes.
A1 preposition /ɒn/

on

sobre
Meaning
physically in contact with and supported by a surface
Example
The book is on the table.
El libro está sobre la mesa.
B2 adjective /aʊtˈstændɪŋ/

outstanding

extraordinario
Meaning
extremely good or impressive; not yet resolved or paid
Example
She received an award for her outstanding performance.
Recibió un premio por su actuación extraordinaria.
B1 verb অকার্স

occurs

sucede
Meaning
Happens or takes place, especially as a result of something.
Example
Snowfall occurs in regions with freezing temperatures.
La nieve ocurre en regiones con temperaturas bajo cero.
C1 noun /ˌəʊvərɪksˌplɔɪˈteɪʃən/

overexploitation

sobreexplotación
Meaning
The unsustainable use of natural resources at a rate that exceeds their ability to regenerate, leading to depletion and environmental degradation.
Example
Overexploitation of natural resources leads to environmental degradation.
La sobreexplotación de los recursos naturales conduce a la degradación ambiental.
C1 verb /ˌaʊtˈduː/

outdo

superar
Meaning
To do better than someone else; to surpass.
Example
She always tries to outdo her classmates in exams.
Ella siempre trata de superar a sus compañeros de clase en los exámenes.
C1 verb /ˈoʊvərˌhɔːl/

overhaul

revisión completa
Meaning
to examine thoroughly and repair or improve something that is worn or ineffective
Example
The company decided to overhaul its outdated computer system.
La compañía decidió hacer una revisión completa a su sistema de computadoras obsoleto.
A1 adjective /əʊˈkeɪ/

okay

está bien
Meaning
used to express agreement or acceptance
Example
It's okay to leave early today.
Está bien irse temprano hoy.
A2 adjective /ˈaʊtdɔːr/

outdoor

al aire libre
Meaning
situated, existing, or done outside a building
Example
We planned an outdoor picnic for the weekend.
Planeamos un picnic al aire libre para el fin de semana.
B2 noun /ˈaʊtlet/

outlet

salida
Meaning
a means by which something is released, expressed, or distributed
Example
Art is a great outlet for emotions.
El arte es una gran salida para las emociones.
C2 adjective /ˈəʊ.dər.əs/

Odorous

fragante; aromático
Meaning
having a strong smell; fragrant; aromatic
Example
The garden was filled with odorous flowers.
El jardín estaba lleno de flores fragantes.
A2 noun /ˈɒpərə/

opera

ópera
Meaning
a dramatic performance in which the actors sing most of their lines
Example
We watched a beautiful opera at the theater last night.
Vimos una hermosa ópera en el teatro anoche.
A2 pronoun /aʊərˈsɛlvz/

ourselves

nosotros mismos
Meaning
used by the speaker to refer to themselves and one or more others as the object of the verb
Example
We should help ourselves before helping others.
Debemos ayudarnos a nosotros mismos antes de ayudar a los demás.
B2 verb /ˌoʊvərˈtɜrn/

overturn

dar la vuelta / revertir una decisión
Meaning
to turn something upside down or to reverse a decision or judgment
Example
The court decided to overturn the previous ruling.
El tribunal decidió anular la decisión anterior.
B1 adjective /əˈrɪdʒ.ɪ.nəl/

Original

original; primario; auténtico
Meaning
first; fundamental; primary; authentic
Example
This is the original document, not a copy.
Este es el documento original, no una copia.
B2 noun /ˈɒp.tɪ.mɪ.zəm/

optimism

optimismo
Meaning
Hopefulness and confidence about the future or the successful outcome of something.
Example
Her optimism helped her overcome difficult times.
Su optimismo le ayudó a superar tiempos difíciles.
A2 noun /ˈoʊ.ʃən/

ocean

océano
Meaning
A very large expanse of sea, especially the main areas of sea between continents.
Example
The ocean covers more than 70% of the Earth's surface.
El océano cubre más del 70% de la superficie de la Tierra.
B1 noun /ˈɔːfɪsər/

officer

oficial
Meaning
a person in a position of authority, especially in law enforcement
Example
The officer gave him a ticket for speeding.
El oficial le dio una multa por exceso de velocidad.
B2 noun /ˈɒs.trɪtʃ/

Ostrich

avestruz
Meaning
a large flightless bird native to Africa with long legs and neck
Example
The ostrich is the world's largest bird.
El avestruz es el pájaro más grande del mundo.
C1 adjective /ɒˈstɛnsəbl/

ostensible

aparente
Meaning
stated or appearing to be true, but not necessarily so
Example
His ostensible reason for leaving was illness, but many doubted it.
Su aparente razón para irse era la enfermedad, pero muchos lo dudaron.
C2 noun /ɒkˈteɪvoʊ/

octavo

octavo (tamaño de libro resultante de doblar una hoja en ocho partes)
Meaning
A size of book page resulting from folding a sheet of paper into eight leaves (sixteen pages).
Example
The old library contained rare octavo editions of Shakespeare.
La antigua biblioteca contenía ediciones raras de octavo de Shakespeare.
A2 adjective /ˈɒb.vi.əs/

Obvious

obvio; fácil de entender
Meaning
easily perceived or understood; clear and apparent to the mind
Example
It was obvious that she was upset about something.
Era obvio que ella estaba molesta por algo.
A2 verb /oʊˈbeɪ/

obey

obedecer
Meaning
to follow orders or instructions; to comply with rules
Example
Children should obey their parents and teachers.
Los niños deben obedecer a sus padres y maestros.
B2 verb /ˌoʊvərˈpeɪ/

overpay

pagar en exceso
Meaning
To pay more than is necessary or reasonable.
Example
She realized she had overpaid for the concert tickets.
Ella se dio cuenta de que había pagado de más por las entradas del concierto.
B2 noun /ˈɔːrnəmənt/

ornament

adorno
Meaning
A decorative object that adds beauty to something.
Example
The Christmas tree was decorated with colorful ornaments.
El árbol de Navidad estaba decorado con adornos de colores.
C2 noun /ˈoʊpiət/

opiate

opiáceo
Meaning
a drug containing opium or its derivatives, used to relieve pain or cause sleep
Example
The doctor prescribed an opiate to relieve the patient's pain.
El médico recetó un opiáceo para aliviar el dolor del paciente.
B1 adjective /ˌoʊvərˈweɪt/

overweight

sobrepeso
Meaning
heavier than is considered healthy or normal
Example
The doctor advised him to lose weight as he was overweight.
El doctor le aconsejó perder peso ya que tenía sobrepeso.
C2 adjective /ˈoʊ.pən ˈhæn.dɪd/

Open-handed

generoso; liberal
Meaning
Generous; liberal; giving freely;
Example
He is very open-handed with his money and always helps those in need.
Él es muy generoso con su dinero y siempre ayuda a los necesitados.
A2 modal verb /ɔːt/

ought

debería
Meaning
Used to indicate duty, correctness, or moral obligation.
Example
You ought to respect your elders.
Deberías respetar a tus mayores.
C1 noun ˌɒb.səˈlɛs.əns

obsolescence

obsolescencia
Meaning
The process of becoming obsolete or outdated and no longer used.
Example
The rapid advancement of technology leads to the obsolescence of old devices.
El rápido avance de la tecnología provoca la obsolescencia de los dispositivos antiguos.
A2 noun əˈlɪm.pɪk ɡeɪmz

Olympic Games

juegos olímpicos
Meaning
The world's largest international sports competition held every four years, bringing together athletes from different countries to compete in various sports.
Example
The Olympic Games bring together the world's top athletes.
Los Juegos Olímpicos reúnen a los mejores atletas del mundo.
B2 noun /əˈpoʊ.nənt/

Opponent

oponente; rival
Meaning
a person who disagrees with or resists a proposal or practice; someone who competes against another
Example
The chess player defeated his strongest opponent.
El jugador de ajedrez derrotó a su oponente más fuerte.
C2 noun ˈɒpjʊləns

opulence

opulencia
Meaning
Great wealth or luxuriousness.
Example
The opulence of the mansion was evident in its ornate furnishings.
La opulencia de la mansión era evidente en sus muebles ornamentados.
A2 noun /ˈɒf.ɪs/

office

oficina
Meaning
a room or building where people work, usually at desks
Example
She left the office early to attend a family event.
Ella dejó la oficina temprano para asistir a un evento familiar.
B2 adjective /ˈɔɪl.i/

Oily

oleoso; cubierto de aceite; grasoso
Meaning
covered with oil; containing oil; greasy
Example
Her oily skin needs special care.
Su piel aceitosa necesita cuidados especiales.
C2 noun /ˈɒksɪdənt/

occident

occidente
Meaning
The countries of the West, especially Europe and America.
Example
The Occident has a long history of philosophical thought.
El occidente tiene una larga historia de pensamiento filosófico.
B2 noun /ˈɔr.fən/

Orphan

huérfano
Meaning
a child whose parents are dead; someone without protective support
Example
The orphan was adopted by a loving family.
El huérfano fue adoptado por una familia amorosa.
C2 verb /ˈɒsɪfaɪ/

ossify

osificar
Meaning
to turn into bone or become rigid and inflexible
Example
With age, some tissues tend to ossify.
Con la edad, algunos tejidos tienden a osificarse.
C1 adjective /əˈblaɪdʒɪŋ/

obliging

servicial
Meaning
Willing to help or do favors; accommodating.
Example
The staff at the hotel were very obliging and friendly.
El personal del hotel era muy servicial y amable.
C1 adjective ˈɒb.stɪ.nət

obstinate

obstinado
Meaning
Refusing to change one's mind or accept others' advice easily.
Example
He remained obstinate despite the logical arguments.
Él se mantuvo obstinado a pesar de los argumentos lógicos.
A2 adjective /əˈlɪmpɪk/

olympic

olímpico
Meaning
related to the Olympic Games, a major international sporting event
Example
She trained hard to compete in the Olympic Games.
Ella entrenó duro para competir en los Juegos Olímpicos.
A2 adverb /ˈɒbviəsli/

obviously

obviamente
Meaning
in a way that is easily perceived or understood; clearly
Example
Obviously, he didn’t read the instructions.
Obviamente, él no leyó las instrucciones.
C1 noun ˌoʊ.vɚˈɡreɪ.zɪŋ

overgrazing

sobrepastoreo
Meaning
The practice of allowing livestock to graze to the point of damaging vegetation.
Example
Overgrazing leads to soil erosion and loss of biodiversity.
El sobrepastoreo lleva a la erosión del suelo y la pérdida de biodiversidad.
B1 noun /ˈɑp.ʃən/

Option

opción
Meaning
a thing that is or may be chosen; an alternative course of action
Example
You have the option to work from home or office.
Tienes la opción de trabajar desde casa o desde la oficina.
C2 noun /ɑːlˈfækʃən/

olfaction

olfato
Meaning
The sense of smell; the process of detecting and perceiving odors.
Example
Dogs have a highly developed sense of olfaction.
Los perros tienen un sentido del olfato muy desarrollado.
B2 noun /ˈaʊt.saɪ.dər/

Out-sider

extranjero
Meaning
a person who does not belong to a particular group; someone not accepted by a group
Example
As an outsider, he found it difficult to understand their traditions.
Como extranjero, le resultó difícil entender sus tradiciones.
C1 adjective /ˌaʊtˈspoʊkən/

Outspoken

franco
Meaning
frank; speaking directly
Example
She is known for being outspoken about social issues.
Es conocida por ser franca sobre los problemas sociales.
B2 adverb /ˈaʊtraɪt/

Outright

directamente; completamente; sin reservas
Meaning
completely; directly; without reservation or concealment
Example
She rejected the proposal outright.
Ella rechazó la propuesta directamente.
B2 noun /ˌɑb.lɪˈɡeɪ.ʃən/

Obligation

obligación
Meaning
a duty or commitment; something that must be done legally or morally
Example
Parents have an obligation to care for their children.
Los padres tienen la obligación de cuidar a sus hijos.
B2 adjective /ˈaʊtˌɡoʊɪŋ/

outgoing

sociable
Meaning
Friendly and sociable; inclined to mix with others.
Example
He is an outgoing person who loves meeting new people.
Es una persona sociable a la que le encanta conocer gente nueva.
C1 adjective /ˈɑp.ər.ə.tɪv/

Operative

activo; en efecto; funcionando; operativo;
Meaning
Functioning; in effect; working; active;
Example
The new safety protocols became operative immediately after the accident.
Los nuevos protocolos de seguridad se volvieron operativos inmediatamente después del accidente.
C1 verb /əbˈstrʌkt/

obstruct

obstruir
Meaning
to block or hinder progress; to prevent or impede movement
Example
The fallen tree obstructed the road for several hours.
El árbol caído obstruyó el camino durante varias horas.
C1 noun ˌɒp.tɪ.maɪˈzeɪ.ʃən

optimization

optimización
Meaning
Improving processes to increase performance and efficiency.
Example
SEO optimization helps websites rank higher on search engines.
La optimización de SEO ayuda a los sitios web a obtener un rango más alto en los motores de búsqueda.
B2 noun /ˈaʊt.breɪk/

Out-break

brote
Meaning
a sudden occurrence or eruption of something, especially disease or violence
Example
The outbreak of flu affected many students in the school.
El brote de gripe afectó a muchos estudiantes en la escuela.
C2 verb /əbˈvɜːrt/

obvert

invertir
Meaning
To turn something so as to face in a different direction; in logic, to convert a proposition by negating both subject and predicate.
Example
The teacher asked the students to obvert the statement for practice.
El maestro pidió a los estudiantes que obvirtieran la declaración para practicar.
C2 noun /ɒmˈnɪʃəns/

omniscience

omnisciencia
Meaning
the state of knowing everything
Example
The novel's narrator has an air of omniscience, revealing every character's thoughts.
El narrador de la novela tiene un aire de omnisciencia, revelando los pensamientos de cada personaje.
C2 noun /oʊˈbeɪsəns/

obeisance

reverencia
Meaning
A gesture of respect such as a bow or curtsy.
Example
They bowed in obeisance to the king.
Ellos se inclinaron en reverencia al rey.