ornithologist
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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.
A2 adjective /ˈɔː.dɪ.nər.i/

Ordinary

ordinario; común; no especial
Meaning
normal; usual; not special
Example
It was just an ordinary day at the office.
Era solo un día ordinario en la oficina.
C1 noun /ˈɔr.ə.kəl/

Oracle

oráculo
Meaning
a person regarded as a source of wise counsel; in ancient times, a priest or priestess acting as a medium
Example
The ancient Greeks consulted the oracle at Delphi.
Los antiguos griegos consultaban el oráculo en Delfos.
B1 adjective /əˈbiː.di.ənt/

Obedient

obediente
Meaning
willing to comply with orders or instructions; submissive
Example
The obedient student always follows the teacher's instructions.
El estudiante obediente siempre sigue las instrucciones del profesor.
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.
B2 noun /ˈaʊtskɜːrts/

outskirts

afueras de la ciudad
Meaning
The outer parts of a town or city, away from the center.
Example
They moved to the outskirts of the city for a quieter life.
Se mudaron a las afueras de la ciudad para una vida más tranquila.
A1 adjective /oʊld/

old

viejo
Meaning
having lived for a long time; not new or young
Example
He still drives his old car.
Él todavía conduce su coche viejo.
C2 noun /ˈoʊɡər/

ogre

ogro
Meaning
A mythical monster, often depicted as large, hideous, and cruel; metaphorically, a cruel or terrifying person.
Example
The villagers feared the ogre who lived in the dark forest.
Los aldeanos temían al ogro que vivía en el bosque oscuro.
B1 noun /ˌɒp.əˈtjuː.nə.ti/

opportunity

oportunidad
Meaning
A favorable chance or set of circumstances that makes it possible to do something.
Example
She seized the opportunity to study abroad.
Ella aprovechó la oportunidad de estudiar en el extranjero.
C1 verb /aʊtˈwɪt/

outwit

superar con astucia
Meaning
to defeat or gain an advantage over someone by being more clever or cunning
Example
The fox managed to outwit the hunters.
El zorro logró engañar a los cazadores.
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 noun /ɔːˈreɪʃən/

oration

discurso
Meaning
A formal speech, especially one given on a ceremonial occasion
Example
The president delivered an inspiring oration.
El presidente dio un discurso inspirador.
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 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.
C1 noun /əbˈzɜːrvətɔːri/

observatory

observatorio
Meaning
A building equipped for observing astronomical or meteorological events.
Example
The observatory is open to the public on weekends.
El observatorio está abierto al público los fines de semana.
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.
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.
C2 adjective /ˈɒf.biːt/

offbeat

inusual
Meaning
Unusual, unconventional, or different from the norm.
Example
She has a very offbeat sense of humor.
Ella tiene un sentido del humor muy inusual.
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.
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 adjective /ˈɒp.tɪ.məl/

optimal

óptimo, más favorable
Meaning
Best or most favorable; the most effective under particular conditions.
Example
The optimal temperature for plant growth is around 25°C.
La temperatura óptima para el crecimiento de las plantas es de alrededor de 25°C.
A2 adverb; noun /ˌaʊtˈdɔːrz/

outdoors

al aire libre
Meaning
outside a building; the natural environment outside
Example
We spent the whole afternoon outdoors enjoying the fresh air.
Pasamos toda la tarde al aire libre disfrutando del aire fresco.
C1 noun /ˌɑːsɪˈleɪʃən/

oscillation

oscilación
Meaning
The movement back and forth at a regular speed.
Example
The oscillation of the pendulum controls the clock.
La oscilación del péndulo controla el reloj.
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.
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.
B2 noun /əbˈdʒek.ʃən/

Objection

objeción; desacuerdo; protesta;
Meaning
an expression of disagreement or disapproval; a reason for disagreeing
Example
The lawyer raised an objection during the trial.
El abogado levantó una objeción durante el juicio.
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.
C1 adjective /əbˈdʒek.ʃən.ə.bəl/

Objectionable

objecionable
Meaning
arousing distaste or opposition; unpleasant or offensive
Example
His objectionable behavior made everyone uncomfortable.
Su comportamiento objetable hizo que todos se sintieran incómodos.
B2 verb /ˌoʊvərˈduː/

overdo

exagerar
Meaning
to do something too much; to exaggerate or carry to excess
Example
Don't overdo the exercise on your first day at the gym.
No exageres con el ejercicio en tu primer día en el gimnasio.
C1 verb /ɔːrˈdeɪn/

ordain

ordenar
Meaning
To officially make someone a priest or minister; to decree or order something officially.
Example
The bishop will ordain three new priests this Sunday.
El obispo ordenará tres nuevos sacerdotes este domingo.
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.
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.
C1 noun /ˈɔr.i.ənt/

Orient

Oriente, especialmente los países de Asia oriental
Meaning
the East, especially countries of eastern Asia; to determine one's position or direction
Example
Many spices come from the Orient.
Muchas especias vienen del Oriente.
B2 noun /ˈaʊtbɜːrst/

outburst

explosión repentina de ira o emoción
Meaning
a sudden release of strong emotion or activity
Example
She had an angry outburst during the meeting.
Ella tuvo una explosión de ira durante la reunión.
C1 noun ˌɒk.sɪˈdeɪ.ʃən

oxidation

oxidación
Meaning
A chemical reaction that involves the combination of a substance with oxygen, often causing deterioration.
Example
Oxidation causes metal surfaces to weaken.
La oxidación debilita las superficies metálicas.
B1 adverb /əˈrɪdʒɪnəli/

originally

originalmente
Meaning
in the beginning, at first
Example
Originally, she wanted to be a doctor.
Originalmente, ella quería ser doctora.
C2 adjective /ˈɒsiəs/

osseous

óseo
Meaning
consisting of or turned into bone; bony
Example
The fossil showed osseous structures of the ancient creature.
El fósil mostró estructuras óseas de la antigua criatura.
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.
C1 noun/verb /ˈoʊvərˌhæŋ/

overhang

saliente
Meaning
To extend outward and hang over something; a projecting part.
Example
The roof overhang provides shade in the summer.
El alero proporciona sombra en el verano.
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.
C1 noun /ˈoʊvərˌtoʊn/

overtone

implicación sutil
Meaning
A subtle quality, implication, or additional meaning beyond the obvious.
Example
His speech had political overtones that were hard to ignore.
Su discurso tenía connotaciones políticas que eran difíciles de ignorar.
B2 verb /əˈrɪdʒɪneɪt/

originate

originar
Meaning
to come into existence; to begin; to create or produce
Example
The tradition originated in ancient times.
La tradición se originó en tiempos antiguos.
C2 noun /ˈɑb.lə.kwi/

Obloquy

crítica severa o abuso verbal; condena pública
Meaning
harsh criticism or verbal abuse; strong public condemnation
Example
The politician faced obloquy after the scandal.
El político enfrentó obloquio después del escándalo.
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.
C2 adjective /ˈɑːsɪˌfaɪd/

ossified

convertido en hueso, rígido
Meaning
Turned into bone or become rigid; unwilling to change.
Example
The company had an ossified management structure that resisted innovation.
La empresa tenía una estructura de gestión rígida que resistía la innovación.
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.
B1 adjective /ˈaʊtər/

outer

exterior
Meaning
situated on or toward the outside; external
Example
The outer layer of the jacket is waterproof.
La capa externa de la chaqueta es impermeable.
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.
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 /ˈoʊ.vər.let/

Overlet

colchón adicional
Meaning
a thin mattress or pad placed over a bed for additional comfort
Example
The overlet makes the bed more comfortable to sleep on.
El overlet hace la cama más cómoda para dormir.
C1 verb /ˌoʊvərˈpaʊər/

overpower

dominar
Meaning
To defeat or gain control over someone or something by using greater strength or force.
Example
The soldiers managed to overpower the enemy forces.
Los soldados lograron dominar las fuerzas enemigas.
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 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.
A1 pronoun /aʊərz/

ours

nuestro
Meaning
belonging to or associated with us
Example
This victory is ours.
Esta victoria es nuestra.
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.
C1 noun /ˈɒn.slɔːt/

onslaught

asalto
Meaning
A fierce or destructive attack.
Example
The village faced an onslaught of enemy forces.
El pueblo enfrentó un asalto de las fuerzas enemigas.
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.
C1 adjective /əbˈsɛsɪv/

obsessive

obsesivo
Meaning
Relating to or characterized by an obsession; thinking about something too much.
Example
He has an obsessive interest in cleanliness.
Él tiene un interés obsesivo en la limpieza.
B2 adjective /ˌɑːp.təˈmɪs.tɪk/

optimistic

optimista
Meaning
hopeful and confident about the future
Example
She is optimistic about the success of her new project.
Ella está optimista acerca del éxito de su nuevo proyecto.
C1 verb /ˈɒp.tɪ.maɪz/

optimize

optimizar
Meaning
To make the best or most effective use of a situation, opportunity, or resource.
Example
The company is working to optimize its supply chain.
La empresa está trabajando para optimizar su cadena de suministro.
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 noun /ˌɑb.zɚˈveɪ.ʃən/

Observation

observación
Meaning
the action of watching something carefully; a comment or remark
Example
The scientist made careful observations of the experiment.
El científico hizo observaciones cuidadosas del experimento.
B2 noun /ˈaʊtlʊk/

outlook

perspectiva, pronóstico
Meaning
a person's general attitude or view; a forecast or prospect
Example
The economic outlook for the year is positive.
El pronóstico económico para el año es positivo.
C2 verb /aʊtˈraɪd/

outride

adelantar
Meaning
to ride faster, farther, or better than someone else
Example
The young rider managed to outride his competitors in the race.
El joven jinete logró adelantar a sus competidores en la carrera.
C2 adjective /əˈrækjələr/

oracular

oracular
Meaning
Resembling an oracle; giving wise, mysterious, or prophetic statements
Example
Her oracular words left the audience deep in thought.
Sus palabras oraculares dejaron a la audiencia profundamente pensativa.
C1 noun /ˈɒfʃuːt/

offshoot

ramificación
Meaning
A branch or result that develops from something larger or more important.
Example
The startup was an offshoot of a major tech company.
La startup fue una ramificación de una gran empresa de tecnología.
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.
C1 noun /ˌɒk.sɪ.dʒɪˈneɪ.ʃən/

oxygenation

suministro o tratamiento con oxígeno
Meaning
The process of supplying or treating with oxygen.
Example
Deep breathing exercises improve oxygenation of the body.
Los ejercicios de respiración profunda mejoran el suministro de oxígeno en el cuerpo.
B1 noun əbˈdʒek.tɪv

objective

objetivo
Meaning
A thing aimed at or sought; a goal.
Example
The main objective is to test sustainability.
El objetivo principal es probar la sostenibilidad.
C2 noun /ˈoʊvərlɔːrd/

overlord

señor
Meaning
A ruler, master, or person of great power and authority over others.
Example
The peasants were forced to pay taxes to their overlord.
Los campesinos fueron obligados a pagar impuestos a su señor.
C2 verb /əbˈtruːd/

obtrude

obstruir
Meaning
to force oneself or one's ideas into a situation uninvited or inappropriately
Example
He didn’t want to obtrude into their private conversation.
Él no quería obstruir su conversación privada.
C1 verb /aʊst/

oust

destituir
Meaning
To remove someone from a position or place of power or authority.
Example
The rebels ousted the dictator from power.
Los rebeldes destituyeron al dictador del poder.
A1 pronoun /aʊər/

our

nuestro
Meaning
belonging to or associated with the speaker and one or more other people
Example
This is our house.
Esta es nuestra casa.
C2 verb /əˈkluːd/

occlude

ocluir
Meaning
To block or close up an opening or passage.
Example
The pipe was occluded by mineral deposits.
La tubería estaba ocluida por depósitos minerales.
C1 noun /ɒpˈtɒmɪtrɪst/

optometrist

optometrista
Meaning
A healthcare professional who examines eyes and prescribes corrective lenses.
Example
The optometrist prescribed new glasses for her.
El optometrista le recetó nuevos anteojos.
C1 noun /ˈɑd.ɪ.ti/

Oddity

rareza
Meaning
something that is strange or unusual; a peculiar trait
Example
His habit of sleeping standing up was considered an oddity.
Su hábito de dormir de pie se consideraba una rareza.
C2 adjective /ɒmˈnɪʃ.ənt/

Omniscient

omnisciente
Meaning
having complete knowledge; all-knowing
Example
The narrator in the novel appears to be omniscient, knowing every character's thoughts.
El narrador en la novela parece ser omnisciente, conociendo todos los pensamientos de los personajes.
C2 noun /oʊd/

ode

oda
Meaning
a lyrical poem, often expressing praise or strong emotions
Example
The poet wrote an ode to the beauty of nature.
El poeta escribió una oda a la belleza de la naturaleza.
A2 noun /əˈlɪmpɪks/

olympics

Juegos Olímpicos
Meaning
an international sports competition held every four years with athletes from many countries
Example
The Olympics bring athletes from all over the world together.
Los Juegos Olímpicos reúnen a atletas de todo el mundo.
B2 noun ˈəʊnəʃɪp

ownership

propiedad
Meaning
The act, state, or right of possessing something; legal title to something.
Example
Ownership of resources was crucial.
La propiedad de los recursos fue crucial.
C2 noun (plural) /ˈɔːrdʒiːz/

orgies

orgías
Meaning
Wild gatherings involving excessive indulgence in food, drink, or sexual activity.
Example
The ancient Romans were infamous for their lavish feasts and orgies.
Los antiguos romanos eran infames por sus banquetes lujosos y orgías.
A1 adverb /ɔːf/

off

apagado
Meaning
away from a place, position, or time; not functioning
Example
He turned off the light before leaving the room.
Apagó la luz antes de salir de la habitación.
B2 adjective ˌɒp.ərˈeɪ.ʃən.əl

operational

operativo
Meaning
In working order; ready for use.
Example
The space project will be operational by 2025.
El proyecto espacial estará operativo para 2025.
C1 adjective /ˈəʊnərəs/

onerous

arduo
Meaning
involving a great deal of effort, difficulty, or burden
Example
Fulfilling the contract proved to be an onerous task for the company.
Cumplir el contrato resultó ser una tarea ardua para la empresa.
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 /ˈaʊtˌsɛt/

outset

comienzo
Meaning
the beginning or start of something
Example
From the outset, the project seemed ambitious but achievable.
Desde el comienzo, el proyecto parecía ambicioso pero alcanzable.
C1 adjective ˈɒk.sɪ.də.tɪv

oxidative

Relacionado con la oxidación
Meaning
Related to or caused by oxidation, especially cellular damage from free radicals.
Example
Excess stress can lead to oxidative damage in cells.
El estrés excesivo puede causar daño oxidativo en las células.
C1 verb /ˌoʊvərˈrʌn/

overrun

invadir
Meaning
to spread over or occupy completely; to exceed a limit or time
Example
The garden was overrun with weeds.
El jardín estaba invadido de maleza.
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.
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.
C1 noun /ˈaʊtˌkraɪ/

outcry

protesta
Meaning
A strong expression of public anger or disapproval.
Example
The decision sparked an outcry among the citizens.
La decisión provocó una protesta entre los ciudadanos.
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.
A1 adjective /oʊˈkeɪ/

ok

está bien
Meaning
used to indicate agreement, approval, or understanding
Example
Okay, let's go to the park.
Está bien, vamos al parque.
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.
C1 noun /ˈɒf.sprɪŋ/

offspring

descendencia
Meaning
a person's child or children; an animal's young
Example
The bird carefully fed its offspring.
El pájaro alimentó cuidadosamente a su descendencia.
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.
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 verb /əˈfend/

offend

ofender
Meaning
to cause displeasure or resentment; to hurt someone's feelings
Example
His rude comments offended many people at the meeting.
Sus comentarios groseros ofendieron a muchas personas en la reunión.
C1 adjective /ˌɒstɛnˈteɪʃəs/

ostentatious

ostentoso
Meaning
Characterized by a showy or pretentious display intended to impress others.
Example
He wore an ostentatious gold chain to the party.
Llevaba una cadena de oro ostentosa en la fiesta.
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 /ˈɒrɪz(ə)n/

orison

oración
Meaning
a prayer, especially a devout or formal one
Example
He whispered a quiet orison before going to sleep.
Susurró una oración tranquila antes de dormir.
C1 adjective /oʊˈvɜːrt/

overt

abierto
Meaning
Done or shown openly; not hidden or secret.
Example
There was an overt display of hostility between the rivals.
Hubo una exhibición abierta de hostilidad entre los rivales.
B1 noun /ˈɑb.stə.kəl/

Obstacle

obstáculo
Meaning
something that blocks or makes progress difficult; a barrier
Example
Bad weather was the main obstacle to our journey.
El mal tiempo fue el principal obstáculo para nuestro viaje.
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.
C1 adjective /ˌoʊvərˈbloʊn/

overblown

exagerado
Meaning
excessively exaggerated or inflated
Example
The controversy was overblown by the media.
La controversia fue exagerada por los medios.
B1 noun /əˈpɪn.jən/

Opinion

opinión
Meaning
a view or judgment formed about something; a belief or assessment based on grounds short of proof
Example
In my opinion, this is the best solution.
En mi opinión, esta es la mejor solución.
C2 noun /oʊf/

Oaf

una persona torpe, estúpida o insensible
Meaning
a clumsy, stupid, or insensitive person
Example
Don't be such an oaf - handle the dishes carefully!
¡No seas un oaf así - maneja los platos con cuidado!
C1 adjective /əˈkʌlt/

occult

oculto
Meaning
Relating to mysterious, supernatural, or magical powers and practices.
Example
She had always been fascinated by the occult and its hidden knowledge.
Ella siempre estuvo fascinada por lo oculto y su conocimiento oculto.
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.
C1 noun /əˈpreʃ.ən/

Oppression

opresión; abuso; tiranía;
Meaning
cruel or unjust treatment or exercise of authority; the state of being subject to harsh treatment
Example
The people fought against political oppression.
La gente luchó contra la opresión política.
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.
B2 noun /oʊk/

oak

roble
Meaning
a large tree that produces acorns and has strong, hard wood
Example
The old oak tree provided shade for the entire yard.
El viejo roble dio sombra a todo el jardín.
C2 adjective /ˌoʊvərˈwiːnɪŋ/

overweening

excesivamente arrogante
Meaning
excessively arrogant or prideful
Example
His overweening pride cost him many friends.
Su exceso de orgullo le costó muchos amigos.
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.
C2 noun /oʊˈbleɪʃən/

oblation

oblación
Meaning
a religious offering, especially of bread or wine to God
Example
The priest placed the oblation on the altar during the ceremony.
El sacerdote colocó la oblación en el altar durante la ceremonia.
C1 adjective /ˈɒm.ɪ.nəs/

Ominous

ominoso; amenazante
Meaning
giving the impression that something bad will happen; threatening; foreboding
Example
The dark clouds looked ominous before the storm.
Las nubes oscuras se veían ominosas antes de la tormenta.
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 /ˌaʊt ən ˈaʊt/

out-and-out

completo
Meaning
complete; absolute; used to emphasize something extreme
Example
The speech was an out-and-out lie.
El discurso fue una mentira completa.
C1 verb əˈblɪt.ə.reɪt

obliterate

destruir
Meaning
To destroy utterly; wipe out completely, to erase or remove something completely.
Example
The storm obliterated entire villages.
La tormenta destruyó aldeas enteras.
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.
B2 noun ɔːˈɡæn.ɪk fuːdz

organic foods

alimentos orgánicos
Meaning
Food produced without the use of chemicals such as artificial pesticides, fertilizers, or other artificial agents.
Example
Organic foods are healthier than processed foods.
Los alimentos orgánicos son más saludables que los alimentos procesados.