oblivious
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C1 adjective əˈblɪv.i.əs

oblivious

ignorant
Meaning
Being completely unaware of surrounding events.
Example
He was oblivious to the noise around him while reading.
Il était inconscient du bruit autour de lui en lisant.
C1 adjective /oʊˈvɜːrt/

overt

ouvert
Meaning
Done or shown openly; not hidden or secret.
Example
There was an overt display of hostility between the rivals.
Il y avait une démonstration ouverte d'hostilité entre les rivaux.
C1 adjective /ˌɒstɛnˈteɪʃəs/

ostentatious

ostentatoire
Meaning
Characterized by a showy or pretentious display intended to impress others.
Example
He wore an ostentatious gold chain to the party.
Il portait une chaîne en or ostentatoire à la fête.
C1 verb /əˈfɪʃieɪt/

officiate

officier
Meaning
To perform official duties, especially in a ceremony or as a referee.
Example
The priest will officiate the wedding ceremony.
Le prêtre officiera la cérémonie de mariage.
C1 noun /ˈɑːdəsi/

odyssey

long voyage
Meaning
a long, adventurous journey; a series of experiences
Example
Her career has been an odyssey of challenges and achievements.
Sa carrière a été une odyssée de défis et de réussites.
C1 noun /ˈaʊtˌɡroʊθ/

outgrowth

croissance
Meaning
something that grows out of something else; a natural development or result
Example
The new policy was an outgrowth of years of debate.
La nouvelle politique était une croissance de plusieurs années de débats.
C1 verb /aʊtˈwɪt/

outwit

déjouer
Meaning
to defeat or gain an advantage over someone by being more clever or cunning
Example
The fox managed to outwit the hunters.
Le renard a réussi à duper les chasseurs.
C1 verb /ˈɒs.ɪ.leɪt/

oscillate

se balancer ou se déplacer d'un point à un autre entre deux états
Meaning
To swing or move back and forth between two points or states
Example
The stock market tends to oscillate during uncertain times.
Le marché boursier a tendance à osciller pendant les périodes incertaines.
C1 adjective /əbˈdʒek.ʃən.ə.bəl/

Objectionable

objectionnable
Meaning
arousing distaste or opposition; unpleasant or offensive
Example
His objectionable behavior made everyone uncomfortable.
Son comportement objectionnable a rendu tout le monde mal à l'aise.
C1 noun /ˈɒn.slɔːt/

onslaught

assaut
Meaning
A fierce or destructive attack.
Example
The village faced an onslaught of enemy forces.
Le village a fait face à un assaut des forces ennemies.
C1 noun /ˈoʊvərˌtoʊn/

overtone

connotation subtile
Meaning
A subtle quality, implication, or additional meaning beyond the obvious.
Example
His speech had political overtones that were hard to ignore.
Son discours avait des connotations politiques qu'il était difficile d'ignorer.
C1 noun /ˈɔːr.ə.tɔːr.i/

oratory

art oratoire
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.
Ses compétences exceptionnelles en oratoire lui ont permis de gagner la compétition de débat.
C1 noun /əbˈzɜːrvətɔːri/

observatory

observatoire
Meaning
A building equipped for observing astronomical or meteorological events.
Example
The observatory is open to the public on weekends.
L'observatoire est ouvert au public le week-end.
C1 adjective /ˌɒmnɪˈprezənt/

omnipresent

omniprésent
Meaning
(of God) present everywhere at the same time.
Example
Social media has become an omnipresent force in modern society.
Les médias sociaux sont devenus une force omniprésente dans la société moderne.
C1 noun /ˌɑːpərˈtuːnɪst/

opportunist

opportuniste
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.
Il est vu comme un opportuniste qui met toujours ses intérêts en premier.
C1 verb /ˌaʊtˈweɪ/

outweigh

avoir plus de poids
Meaning
To be more important, valuable, or significant than something else.
Example
The benefits of the new policy outweigh the risks.
Les avantages de la nouvelle politique l'emportent sur les risques.
C1 adjective /ˈɒptɪkəl/

optical

optique
Meaning
related to or used in seeing or sight
Example
The optical illusion fooled everyone at the exhibition.
L'illusion optique a trompé tout le monde lors de l'exposition.
C1 noun /ˈɔːrkɪd/

Orchid

orchidée
Meaning
a diverse family of flowering plants known for their exotic and often fragrant flowers
Example
The white orchid on the windowsill bloomed for months.
L'orchidée blanche sur le rebord de la fenêtre a fleuri pendant des mois.
C1 adjective əʊˈpeɪk

opaque

opaque, impénétrable, difficile à comprendre
Meaning
Not able to be seen through; not transparent; difficult to understand.
Example
The glass was too opaque to see through.
Le verre était trop opaque pour voir à travers.
C1 noun əˈblɪv.i.ən

oblivion

oubli, destruction, disparition
Meaning
The state of being unaware or unconscious of what is happening; complete forgetfulness.
Example
His name faded into oblivion over time.
Son nom s'est effacé dans l'oubli au fil du temps.
C1 adjective /ˌəʊvərˈstɪmjʊˌleɪtɪd/

overstimulated

trop stimule
Meaning
Excessively excited or aroused, overwhelmed by too much stimulus.
Example
Overstimulated minds can lead to burnout and decreased productivity.
Des esprits trop stimulés peuvent conduire à l'épuisement professionnel et à une diminution de la productivité.
C1 verb /ˌoʊvərˈrʌn/

overrun

envahir
Meaning
to spread over or occupy completely; to exceed a limit or time
Example
The garden was overrun with weeds.
Le jardin était envahi par les mauvaises herbes.
C1 noun /əˈfen.dər/

Offender

délinquant; infractionniste de la loi
Meaning
a person who commits an illegal act; someone who breaks the law
Example
The young offender was sentenced to community service.
Le jeune délinquant a été condamné à des travaux d'intérêt général.
C1 adjective /əˈbliːk/

Oblique

oblique; diagonal; indirect ou évasif
Meaning
slanting; diagonal; indirect or evasive
Example
The artist drew an oblique line across the canvas.
L'artiste a tracé une ligne oblique sur la toile.
C1 adjective ˈɒb.stɪ.nət

obstinate

obstiné
Meaning
Refusing to change one's mind or accept others' advice easily.
Example
He remained obstinate despite the logical arguments.
Il est resté obstiné malgré les arguments logiques.
C1 noun /əbˈzɜːvəns/

observance

observance
Meaning
The practice of following a custom, rule, or religious law.
Example
The festival is held in observance of a centuries-old tradition.
Le festival est organisé en observance d'une tradition séculaire.
C1 adjective /ˈɔːrθədɑːks/

orthodox

orthodoxe
Meaning
conforming to traditional beliefs or practices
Example
He comes from a very orthodox family.
Il vient d'une famille très orthodoxe.
C1 noun /ˌoʊvərprəˈdʌkʃən/

overproduction

surproduction
Meaning
The act of producing more of something than is needed or can be consumed.
Example
The economic crisis was caused by the overproduction of goods.
La crise économique a été causée par la surproduction de biens.
C1 verb /ˌaʊtˈstrɛtʃ/

outstretch

étendre
Meaning
To extend or stretch something outward.
Example
He outstretched his hand to help her up.
Il a tendu la main pour l'aider à se lever.
C1 noun /ˈɑn.set/

Onset

début; commencement
Meaning
the beginning or early stages of something; the start of a medical condition
Example
The onset of winter brought heavy snowfall.
Le début de l'hiver a apporté de fortes chutes de neige.
C1 noun /əbˈstrʌkʃən/

obstruction

obstacle
Meaning
Something that blocks or gets in the way; the action of obstructing.
Example
There was an obstruction on the railway track.
Il y avait un obstacle sur la voie ferrée.
C1 adjective /ˌɑːpərˈtuːn/

opportune

moment opportun
Meaning
Happening at a suitable or convenient time.
Example
She arrived at an opportune moment to help.
Elle est arrivée à un moment opportun pour aider.
C1 noun /ˈɔːrθədɑːksi/

orthodoxy

orthodoxie
Meaning
traditional or generally accepted beliefs and practices
Example
The religious leader defended the orthodoxy of the faith.
Le leader religieux a défendu l'orthodoxie de la foi.
C1 adjective /əbˈtjuːs/

Obtuse

obtus; lent à comprendre; sans intelligence
Meaning
annoyingly insensitive or slow to understand; lacking in intelligence or perception
Example
He was being deliberately obtuse about the instructions.
Il était délibérément obtus à propos des instructions.
C1 adjective /ɔːˈneɪt/

ornate

orné
Meaning
elaborately or highly decorated
Example
The palace hall was filled with ornate furniture and paintings.
La salle du palais était remplie de meubles ornés et de peintures.
C1 noun /ɒpˈtɒmɪtrɪst/

optometrist

optométriste
Meaning
A healthcare professional who examines eyes and prescribes corrective lenses.
Example
The optometrist prescribed new glasses for her.
L'optométriste a prescrit de nouvelles lunettes pour elle.
C1 verb /ˌoʊvərˈʃædoʊ/

overshadow

éclipser
Meaning
to appear more important or significant than something else, reducing its impact
Example
The scandal overshadowed his achievements.
Le scandale a éclipsé ses réalisations.
C1 adjective /ɒmˈnɪv.ər.əs/

Omnivorous

omnivore
Meaning
eating both plants and animals; feeding on various kinds of food
Example
Bears are omnivorous animals that eat both plants and meat.
Les ours sont des animaux omnivores qui mangent à la fois des plantes et de la viande.
C1 verb /ˌaʊtˈstrɪp/

outstrip

dépasser
Meaning
To go faster or do better than someone or something; to surpass.
Example
The company outstripped its competitors in sales last year.
L'entreprise a dépassé ses concurrents en ventes l'année dernière.
C1 verb /ˌoʊvərˈriːtʃ/

overreach

dépassement de soi
Meaning
to go beyond what is proper, acceptable, or achievable; to overextend
Example
The politician overreached by making promises he couldn't keep.
Le politicien a dépassé les limites en faisant des promesses qu'il n'a pas pu tenir.
C1 noun /əˈpreʃ.ən/

Oppression

oppression; abus; tyrannie;
Meaning
cruel or unjust treatment or exercise of authority; the state of being subject to harsh treatment
Example
The people fought against political oppression.
Les gens ont lutté contre l'oppression politique.
C1 adjective /əˈprɛs.ɪv/

Oppressive

oppressif
Meaning
Harsh and authoritarian; overwhelming; causing distress; tyrannical;
Example
The oppressive heat made it difficult to work outside during the summer.
La chaleur oppressante rendait difficile de travailler à l'extérieur pendant l'été.
C1 adjective ˈɒptɪmaɪzd

optimized

optimisé, amélioré, plus efficace
Meaning
Made as fully perfect, functional, or effective as possible; improved to achieve maximum efficiency.
Example
The system has been optimized for faster performance.
Le système a été optimisé pour des performances plus rapides.
C1 noun /ˌɑːk.sɪˈmɔːr.ɒn/

oxymoron

oxymore
Meaning
a figure of speech where two contradictory terms are combined
Example
The phrase 'deafening silence' is a classic oxymoron.
L'expression 'silence assourdissant' est un oxymore classique.
C1 verb /əbˈsɛs/

obsess

obséder
Meaning
To preoccupy or fill the mind of someone continually and to an excessive degree.
Example
She tends to obsess over small details.
Elle a tendance à s'obséder sur de petits détails.
C1 adjective /ˈɔːrdɪnəl/

ordinal

ordinal
Meaning
Relating to the order or position of something in a sequence (first, second, third, etc.).
Example
The ordinal number 'third' indicates position in a sequence.
Le numéro ordinal 'troisième' indique la position dans une séquence.
C1 adjective /əbˈzɜːrvənt/

Observant

observateur
Meaning
quick to notice things; watchful; attentive
Example
The observant detective noticed every small detail at the crime scene.
Le détective observateur a remarqué chaque petit détail sur la scène du crime.
C1 adjective /ˈɑp.ər.ə.tɪv/

Operative

actif; en vigueur; fonctionnant; opérationnel;
Meaning
Functioning; in effect; working; active;
Example
The new safety protocols became operative immediately after the accident.
Les nouveaux protocoles de sécurité sont devenus opérationnels immédiatement après l'accident.
C1 noun /ˈoʊvərˌsiːər/

overseer

superviseur
Meaning
a person who supervises work or workers; a manager
Example
The overseer made sure the workers followed safety rules.
Le superviseur s'est assuré que les travailleurs respectaient les règles de sécurité.
C1 adjective ˈɒk.sɪ.də.tɪv

oxidative

Relatif à l'oxydation
Meaning
Related to or caused by oxidation, especially cellular damage from free radicals.
Example
Excess stress can lead to oxidative damage in cells.
Le stress excessif peut entraîner des dommages oxydatifs dans les cellules.
C1 noun /əˈkɜr.əns/

Occurrence

événement
Meaning
an instance or event of something happening; the fact of occurring
Example
The occurrence of earthquakes is common in this region.
L'occurrence des tremblements de terre est courante dans cette région.
C1 adjective /ˌɔː.riˈen.təl/

Oriental

relatif aux pays de l'Asie de l'Est; oriental
Meaning
relating to the countries of East Asia; eastern
Example
The museum has a beautiful collection of oriental art.
Le musée possède une belle collection d'art oriental.
C1 noun /ˈaʊtriːtʃ/

outreach

expansion de l'aide
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.
L'association a lancé un nouveau programme d'expansion de l'aide pour les sans-abri.
C1 noun /ˈɔr.i.ənt/

Orient

Orient, en particulier les pays d'Asie de l'Est
Meaning
the East, especially countries of eastern Asia; to determine one's position or direction
Example
Many spices come from the Orient.
De nombreuses épices viennent de l'Orient.
C1 noun /oʊˈmɪʃ.ən/

Omission

omission; exclusion
Meaning
the action of excluding or leaving out someone or something; a failure to include
Example
The omission of his name from the list was intentional.
L'omission de son nom de la liste était intentionnelle.
C1 adjective /əˈblaɪdʒɪŋ/

obliging

serviable
Meaning
Willing to help or do favors; accommodating.
Example
The staff at the hotel were very obliging and friendly.
Le personnel de l'hôtel était très serviable et amical.
C1 noun /ˈɒktəɡən/

octagon

octogone
Meaning
A polygon with eight sides and eight angles.
Example
The stop sign is shaped like an octagon.
Le panneau stop a la forme d'un octogone.
C1 adjective /əbˈstrʌk.tɪv/

Obstructive

obstructif
Meaning
deliberately creating difficulties or preventing progress; hindering or blocking something
Example
The obstructive policies hindered economic growth.
Les politiques obstructives ont entravé la croissance économique.
C1 noun /ˈoʊ.mən/

Omen

un signe de bonne ou mauvaise chance future
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.
Beaucoup de gens considèrent qu'un chat noir traversant votre chemin est un mauvais présage.
C1 verb /ˌaʊtˈduː/

outdo

surpasser
Meaning
To do better than someone else; to surpass.
Example
She always tries to outdo her classmates in exams.
Elle essaie toujours de surpasser ses camarades de classe lors des examens.
C1 adjective /əbˈsɛsɪv/

obsessive

obsessionnel
Meaning
Relating to or characterized by an obsession; thinking about something too much.
Example
He has an obsessive interest in cleanliness.
Il a un intérêt obsessionnel pour la propreté.
C1 noun /oʊˈbɪt.ʃu.er.i/

Obituary

nécrologie
Meaning
a notice of someone's death published in a newspaper; biographical account of deceased person
Example
The newspaper published his obituary yesterday.
Le journal a publié son nécrologie hier.
C1 noun /ˈoʊvərˌtʊr/

overture

ouverture / proposition
Meaning
An introduction to something more substantial; a proposal or preliminary action.
Example
The peace overture was welcomed by both nations.
L'ouverture de la paix a été accueillie favorablement par les deux nations.
C1 adjective /ˌaʊt ən ˈaʊt/

out-and-out

complet
Meaning
complete; absolute; used to emphasize something extreme
Example
The speech was an out-and-out lie.
Le discours était un mensonge complet.
C1 verb /ɔːrˈdeɪn/

ordain

ordonner
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.
L'évêque ordonnera trois nouveaux prêtres ce dimanche.
C1 noun /ˈaʊtpoʊst/

outpost

avant-poste
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.
Les soldats étaient stationnés dans un avant-poste éloigné.
C1 adjective /ˈɒptɪməm/

optimum

optimal
Meaning
Most conducive to a favorable outcome; best.
Example
To achieve optimum results, we need to improve efficiency.
Pour obtenir des résultats optimaux, nous devons améliorer l'efficacité.
C1 noun /ˌɒbstəˈtrɪʃən/

obstetrician

obstétricien
Meaning
A doctor specializing in pregnancy, childbirth, and women's reproductive health.
Example
The obstetrician monitored the mother’s health throughout the pregnancy.
L'obstétricien a surveillé la santé de la mère tout au long de la grossesse.
C1 verb /aʊtˈlɪv/

outlive

survivre
Meaning
to live longer than someone or something else
Example
She outlived all her siblings.
Elle a vécu plus longtemps que tous ses frères et sœurs.
C1 noun /ˈɔːrdɪnəns/

ordinance

ordonnance
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.
Le conseil municipal a adopté une ordonnance interdisant de fumer dans les parcs publics.
C1 noun /ˌɒk.sɪ.dʒɪˈneɪ.ʃən/

oxygenation

fourniture ou traitement d'oxygène
Meaning
The process of supplying or treating with oxygen.
Example
Deep breathing exercises improve oxygenation of the body.
Les exercices de respiration profonde améliorent l'oxygénation du corps.
C1 noun /ˈoʊ.vər spɪl/

Over-spill

débordement
Meaning
the overflow of liquid from a container; excess that cannot be contained
Example
The overspill from the river flooded nearby farms.
Le débordement de la rivière a inondé les fermes voisines.
C1 adjective /ˌoʊvərˈbɛrɪŋ/

overbearing

autoritaire
Meaning
unpleasantly or arrogantly domineering
Example
His overbearing attitude made everyone uncomfortable.
Son attitude autoritaire a mis tout le monde mal à l'aise.
C1 noun /oʊθ/

Oath

serment
Meaning
a solemn promise or declaration; a sworn statement
Example
The doctor took an oath to help patients.
Le médecin a prêté serment pour aider les patients.
C1 verb /ˈɔːstrəˌsaɪz/

ostracize

ostraciser
Meaning
to exclude someone from a group or society; to banish or shun
Example
After the scandal, he was ostracized by his former colleagues.
Après le scandale, il a été ostracisé par ses anciens collègues.
C1 noun /ˈɒstrəsɪzəm/

ostracism

ostracisme
Meaning
The act of excluding someone from a group or society.
Example
The student faced ostracism after breaking the rules.
L'étudiant a fait face à l'ostracisme après avoir enfreint les règles.
C1 noun ˈaʊt.sɔːr.sɪŋ

outsourcing

externalisation
Meaning
The practice of having certain job functions done outside a company instead of having an in-house department or employee handle them.
Example
Many companies use outsourcing to reduce labor costs.
De nombreuses entreprises utilisent l'externalisation pour réduire les coûts de main-d'œuvre.
C1 adjective /ɒˈstɛnsəbl/

ostensible

apparente
Meaning
stated or appearing to be true, but not necessarily so
Example
His ostensible reason for leaving was illness, but many doubted it.
Sa raison apparente de partir était la maladie, mais beaucoup en doutaient.
C1 adjective /əbˈnɒkʃəs/

Obnoxious

odieux
Meaning
extremely unpleasant; offensive; annoying
Example
His obnoxious behavior at the party annoyed everyone.
Son comportement odieux à la fête a agacé tout le monde.
C1 noun /ˌɑːsɪˈleɪʃən/

oscillation

oscillation
Meaning
The movement back and forth at a regular speed.
Example
The oscillation of the pendulum controls the clock.
L'oscillation du pendule contrôle l'horloge.
C1 adjective /ˌɔːrθəˈpiːdɪk/

orthopedic

relatif à la correction des déformations osseuses ou musculaires
Meaning
Relating to the correction of deformities of bones or muscles.
Example
She visited an orthopedic surgeon for her back pain.
Elle a consulté un chirurgien orthopédique pour sa douleur au dos.
C1 verb /əbˈstrʌkt/

obstruct

obstruer
Meaning
to block or hinder progress; to prevent or impede movement
Example
The fallen tree obstructed the road for several hours.
L'arbre tombé obstruait la route pendant plusieurs heures.
C1 adjective /aʊtˈmoʊdɪd/

outmoded

démodé
Meaning
No longer in fashion or useful; outdated.
Example
That old computer is completely outmoded.
Cet ancien ordinateur est complètement démodé.
C1 verb /ˌoʊvərˈpaʊər/

overpower

dominer
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.
Les soldats ont réussi à dominer les forces ennemies.
C1 adjective /ˌaʊtˈspoʊkən/

Outspoken

franc
Meaning
frank; speaking directly
Example
She is known for being outspoken about social issues.
Elle est connue pour être franche sur les problèmes sociaux.
C1 noun/verb /ˈoʊvərˌhæŋ/

overhang

saillie
Meaning
To extend outward and hang over something; a projecting part.
Example
The roof overhang provides shade in the summer.
Le surplomb fournit de l'ombre en été.
C1 adjective /ˌəʊ.vərˈɑː.tʃɪŋ/

overarching

global, englobant, tout-en-un
Meaning
Comprehensive or all-embracing; forming an arch over something.
Example
The overarching theme of the book is human resilience.
Le thème global du livre est la résilience humaine.
C1 noun /ˈəʊ.nəs/

onus

responsabilité
Meaning
A duty or responsibility, especially a heavy one.
Example
The onus is on the government to provide relief to the victims.
La responsabilité incombe au gouvernement de fournir de l'aide aux victimes.
C1 adjective /ˈɒptɪk/

optic

optique
Meaning
Relating to the eye or vision.
Example
The optic nerve carries signals from the eye to the brain.
Le nerf optique transporte les signaux de l'œil au cerveau.
C1 verb /ˌoʊvərˈθroʊ/

overthrow

bonheur
Meaning
To remove a leader or government from power, often by force.
Example
The rebels planned to overthrow the corrupt regime.
Elle ne pouvait pas cacher son bonheur lorsqu'elle a reçu le prix.
C1 noun /ˈɒptɪks/

optics

optique
Meaning
The branch of physics dealing with light and vision.
Example
She studied optics to understand how lenses work.
Elle a étudié l'optique pour comprendre comment fonctionnent les lentilles.
C1 adjective /ˌoʊvərˈbloʊn/

overblown

exagéré
Meaning
excessively exaggerated or inflated
Example
The controversy was overblown by the media.
La controverse a été exagérée par les médias.
C1 adjective /ˌɔːrnəˈmɛntl/

ornamental

ornemental
Meaning
Serving as decoration; decorative rather than functional.
Example
The garden was filled with ornamental plants.
Le jardin était rempli de plantes ornementales.
C1 noun /ˈɑd.ɪ.ti/

Oddity

étrangeté
Meaning
something that is strange or unusual; a peculiar trait
Example
His habit of sleeping standing up was considered an oddity.
Son habitude de dormir debout était considérée comme une étrangeté.
C1 adjective /ˌɒbsəˈliːt/

obsolete

obsolète
Meaning
No longer in use or out of date.
Example
Floppy disks are now completely obsolete.
Les disquettes sont maintenant complètement obsolètes.
C1 verb /ˈɒp.tɪ.maɪz/

optimize

optimiser
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.
L'entreprise travaille à optimiser sa chaîne d'approvisionnement.
C1 noun ˈoʊʃən əˌsɪdɪfɪˈkeɪʃən

ocean acidification

acidification océanique
Meaning
The ongoing decrease in the pH of the Earth's oceans, caused by the absorption of carbon dioxide from the atmosphere.
Example
Ocean acidification is caused by atmospheric CO2 absorption.
L'acidification océanique est causée par l'absorption du CO2 atmosphérique.
C1 verb ˈɔː.kɪ.streɪ.tɪd

orchestrated

orchestré
Meaning
Planned or coordinated carefully and deliberately.
Example
The attacks were orchestrated with precision.
Les attaques ont été orchestrées avec précision.
C1 noun ˌɒp.tɪ.maɪˈzeɪ.ʃən

optimization

optimisation
Meaning
Improving processes to increase performance and efficiency.
Example
SEO optimization helps websites rank higher on search engines.
L'optimisation SEO aide les sites web à se classer plus haut dans les moteurs de recherche.
C1 noun /ˈɔr.ə.kəl/

Oracle

oracle
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.
Les anciens Grecs consultaient l'oracle de Delphes.
C1 verb /əˈprɛs/

oppress

opprimer
Meaning
to keep someone down by harsh and unfair use of authority; to suppress
Example
The dictator oppressed the people for decades.
Le dictateur a opprimé les gens pendant des décennies.
C1 adjective/adverb /ˌɒfˈhænd/

offhand

sans réflexion
Meaning
Without previous thought or preparation; casual and sometimes dismissive.
Example
She gave an offhand reply to his serious question.
Elle a donné une réponse sans réfléchir à sa question sérieuse.
C1 noun ɔːrˈdiːl

ordeal

épreuve difficile
Meaning
A physical or mental painful experience that must be endured
Example
Surviving the wilderness was a tough ordeal for them.
Survivre dans la nature a été une épreuve difficile pour eux.
C1 verb əˈblɪt.ə.reɪt

obliterate

anéantir
Meaning
To destroy utterly; wipe out completely, to erase or remove something completely.
Example
The storm obliterated entire villages.
La tempête a anéanti des villages entiers.
C1 noun ˌɒk.sɪˈdeɪ.ʃən

oxidation

oxydation
Meaning
A chemical reaction that involves the combination of a substance with oxygen, often causing deterioration.
Example
Oxidation causes metal surfaces to weaken.
L'oxydation affaiblit les surfaces métalliques.
C1 noun /ˈɒf.sprɪŋ/

offspring

progéniture
Meaning
a person's child or children; an animal's young
Example
The bird carefully fed its offspring.
L'oiseau a nourri soigneusement sa progéniture.
C1 noun /ˈɒktɪv/

octave

octave
Meaning
A series of eight musical notes, or the interval between one musical pitch and another with double its frequency.
Example
The singer's voice could easily reach the higher octave.
La voix du chanteur pourrait facilement atteindre l'octave supérieure.
C1 verb ˈɔːr.kɪ.streɪt

orchestrate

orchestrer
Meaning
To plan or coordinate the elements of (a situation) to produce a desired effect, especially surreptitiously.
Example
He skillfully orchestrated the entire event.
Il a habilement orchestré l'ensemble de l'événement.
C1 verb /uːz/

ooze

suinter
Meaning
to slowly flow or leak out through small openings or pores
Example
Blood began to ooze from the small cut.
Le sang a commencé à suinter de la petite coupure.
C1 adverb /ˈaʊtwədli/

Outwardly

extérieurement; en apparence;
Meaning
on the surface; externally; in appearance
Example
Outwardly, he seemed calm, but inside he was nervous.
Extérieurement, il semblait calme, mais à l'intérieur, il était nerveux.
C1 adjective /ˌoʊvərˈrɔt/

overwrought

agité / excessivement nerveux
Meaning
extremely agitated or nervous; excessively elaborate
Example
She was too overwrought to speak clearly after the accident.
Elle était trop agité pour parler clairement après l'accident.
C1 noun /ˌəʊvərɪksˌplɔɪˈteɪʃən/

overexploitation

surexploitation
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 surexploitation des ressources naturelles conduit à la dégradation de l'environnement.
C1 adjective /ˈaʊt.kɑːst/

Outcast

rejeté
Meaning
rejected by society; excluded person
Example
He felt like an outcast in his new school.
Il s'est senti comme un rejeté dans sa nouvelle école.
C1 verb /ˌoʊvərˈruːl/

overrule

rejeter
Meaning
to reject or disallow by exercising one's superior authority; to override a decision
Example
The judge overruled the objection from the defense attorney.
Le juge a rejeté l'objection de l'avocat de la défense.
C1 noun /oʊˈeɪ.sɪs/

Oasis

oasis
Meaning
a fertile spot in a desert where water is found; a pleasant refuge
Example
The travelers found an oasis after days in the desert.
Les voyageurs ont trouvé un oasis après plusieurs jours dans le désert.
C1 noun /ˈɔr.ə.tər/

Orator

orateur
Meaning
a public speaker, especially one who is eloquent or skilled in speaking
Example
The famous orator delivered an inspiring speech.
Le célèbre orateur a prononcé un discours inspirant.
C1 noun /ˈɔɪntmənt/

ointment

onguent
Meaning
A smooth, oily substance applied to the skin for healing or soothing.
Example
The doctor prescribed an ointment for the burn on his arm.
Le médecin a prescrit un onguent pour la brûlure sur son bras.
C1 noun /ɔːr/

Oar

aviron
Meaning
a long pole with a flat blade used to row a boat
Example
He dipped the oar into the water and pulled the boat forward.
Il plongea l'aviron dans l'eau et tira le bateau en avant.
C1 verb /ˈoʊvərˌhɔːl/

overhaul

révision complète
Meaning
to examine thoroughly and repair or improve something that is worn or ineffective
Example
The company decided to overhaul its outdated computer system.
L'entreprise a décidé de rénover son système informatique obsolète.
C1 adjective /əˈblɪɡ.ə.tɔː.ri/

obligatory

obligatoire
Meaning
Required by a legal, moral, or other rule; compulsory.
Example
Wearing a seatbelt is obligatory in most countries.
Porter une ceinture de sécurité est obligatoire dans la plupart des pays.
C1 noun /ɒpˈtɒmətri/

optometry

optométrie
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.
Elle a étudié l'optométrie à l'université pour devenir spécialiste des yeux.