Opponent
All a b c d e f g h i j k l m n o p q r s t u v w x y z
All CEFR A1 A2 B1 B2 C1 C2
Content locale
EN 英語 BN ベンガル語 HI ヒンディー語 ES スペイン語 FR フランス語 DE ドイツ語 RU ロシア語 ZH 中国語 JA 日本語
All Vocabulary Cards All Vocabularies
B2 noun /əˈpoʊ.nənt/

Opponent

対戦相手; ライバル
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.
チェスのプレーヤーは最強の対戦相手を倒した。
B2 noun /ˈɒp.tɪ.mɪ.zəm/

optimism

楽観主義
Meaning
Hopefulness and confidence about the future or the successful outcome of something.
Example
Her optimism helped her overcome difficult times.
彼女の楽観主義は、困難な時期を乗り越える助けとなりました。
A2 noun /ɔɪl/

Oil

油
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.
野菜を加える前にフライパンで油を温めます。
B2 verb /əbˈteɪn/

obtain

取得する
Meaning
to get or acquire something
Example
You need to obtain a visa before traveling abroad.
あなたは海外に行く前にビザを取得する必要があります。
B2 adjective /ˈɔː.rəl/

Oral

口頭の; 口に関する
Meaning
spoken rather than written; relating to the mouth
Example
The oral examination will test your speaking skills.
口頭試験はあなたの話す能力をテストします。
C1 verb /aʊtˈwɪt/

outwit

巧妙に出し抜く
Meaning
to defeat or gain an advantage over someone by being more clever or cunning
Example
The fox managed to outwit the hunters.
キツネは猟師たちを出し抜くことができました。
B2 verb /əˈblaɪdʒ/

oblige

義務付ける
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.
必要な情報を提供してお手伝いできれば嬉しいです。
C2 noun /ɔːrˈθɑːɡrəfi/

orthography

正書法
Meaning
The conventional spelling system of a language.
Example
English orthography can be confusing for learners.
英語の正書法は学習者にとって混乱を招くことがあります。
C2 adjective /ɒmˈnɪʃ.ənt/

Omniscient

全知の
Meaning
having complete knowledge; all-knowing
Example
The narrator in the novel appears to be omniscient, knowing every character's thoughts.
小説の語り手は全知であるかのようで、すべての登場人物の思考を知っている。
C2 noun /ˌɒstɛnˈteɪʃən/

ostentation

見せびらかし
Meaning
excessive display of wealth or knowledge intended to attract admiration or envy
Example
The billionaire’s party was full of ostentation and luxury.
億万長者のパーティーは、見せびらかしと贅沢で満ちていた。
C2 noun /ˈoʊvərlɔːrd/

overlord

領主
Meaning
A ruler, master, or person of great power and authority over others.
Example
The peasants were forced to pay taxes to their overlord.
農民たちは自分たちの領主に税金を払うよう強制されました。
B2 noun /ˈɔːrnəmənt/

ornament

装飾品
Meaning
A decorative object that adds beauty to something.
Example
The Christmas tree was decorated with colorful ornaments.
クリスマスツリーはカラフルな装飾品で飾られていました。
C2 adjective /ˈoʊ.vɔɪd/

ovoid

卵型
Meaning
egg-shaped; resembling an oval or ellipse
Example
The artist painted an ovoid shape in the center of the canvas.
アーティストはキャンバスの中央に卵型の形を描きました。
B1 adverb /ˈʌðərwaɪz/

Otherwise

さもないと; 他の方法で
Meaning
in a different way; if not; or else; apart from that
Example
Study hard, otherwise you will fail the exam.
一生懸命勉強しなさい、さもないと試験に落ちます。
C1 adjective /ˈɒptɪkəl/

optical

光学的
Meaning
related to or used in seeing or sight
Example
The optical illusion fooled everyone at the exhibition.
その光学的錯覚は展示会で皆を騙した。
A1 pronoun /ˈʌðərz/

others

他の人々
Meaning
people or things distinct from the ones already mentioned or known
Example
I like to spend time with others.
私は他の人々と時間を過ごすのが好きです。
B2 verb /ˌoʊvərˈtɜrn/

overturn

覆す / 判決を覆す
Meaning
to turn something upside down or to reverse a decision or judgment
Example
The court decided to overturn the previous ruling.
裁判所は前回の判決を覆すことに決めました。
C1 noun /ˈɒstrəsɪzəm/

ostracism

追放
Meaning
The act of excluding someone from a group or society.
Example
The student faced ostracism after breaking the rules.
その学生は規則を破った後、追放に直面しました。
B2 noun /ˈɒt.ər/

Otter

カワウソ
Meaning
a mammal with webbed feet that lives near water and feeds on fish
Example
The playful otter swam gracefully in the river.
遊び好きなカワウソは川で優雅に泳いでいました。
C2 noun /ˈɔːrzmən/

Oarsman

オールマン
Meaning
a person who rows a boat, especially as a member of a racing crew
Example
The experienced oarsman rowed the boat across the river.
経験豊富なオールマンは川を渡るためにボートを漕いだ。
C2 noun (plural) /ˈɔːrdʒiːz/

orgies

オルギー
Meaning
Wild gatherings involving excessive indulgence in food, drink, or sexual activity.
Example
The ancient Romans were infamous for their lavish feasts and orgies.
古代ローマ人は豪華な宴会とオルギーで悪名高かった。
A1 adjective /ˈʌðər/

other

他の
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.
これを欲しくない、他のを取るつもりだ。
A1 adverb /wʌns/

Once

一度; 過去に
Meaning
one time only; at some time in the past; formerly
Example
I have been to Paris once in my life.
私は一度だけパリに行ったことがあります。
C1 noun /ˌɑːk.sɪˈmɔːr.ɒn/

oxymoron

オキシモロン
Meaning
a figure of speech where two contradictory terms are combined
Example
The phrase 'deafening silence' is a classic oxymoron.
「耳をつんざくような静けさ」というフレーズは、典型的なオキシモロンです。
C1 verb /ˌoʊvərˈrʌn/

overrun

侵略する
Meaning
to spread over or occupy completely; to exceed a limit or time
Example
The garden was overrun with weeds.
庭は雑草に覆われていた。
B1 verb অকার্স

occurs

起こる
Meaning
Happens or takes place, especially as a result of something.
Example
Snowfall occurs in regions with freezing temperatures.
雪は氷点下の温度を持つ地域で起こります。
B1 adjective, adverb /ˈoʊvərɔːl/

overall

全体的に
Meaning
in general or as a whole
Example
Overall, the project has been successful.
全体的に、プロジェクトは成功しました。
C2 noun ˈoʊʃən ˌstrætɪfɪˈkeɪʃən

ocean stratification

海洋の成層
Meaning
The formation of layers in ocean water due to differences in density.
Example
Ocean stratification affects marine biodiversity.
オーシャンストラティフィケーションは海洋生物多様性に影響を与えます。
C2 verb /ˈɔːreɪt/

orate

演説する
Meaning
To speak in a formal, often pompous manner
Example
He began to orate at the ceremony.
彼は式で演説を始めました。
B2 noun ˈɔː.bɪt

orbit

軌道
Meaning
The curved path of a celestial object around a star, planet, or moon.
Example
The satellite maintains its orbit around Earth.
衛星は地球の周りを軌道上に保っています。
C2 noun /ˈoʊ.kəm/

oakum

古いロープの繊維
Meaning
loose fibers obtained by untwisting old ropes, used for caulking ships
Example
The shipbuilders used oakum to seal the gaps in the wooden planks.
船大工たちは木の板の隙間を塞ぐためにオーカムを使いました。
C1 noun /əˈfen.dər/

Offender

犯罪者; 法律違反者
Meaning
a person who commits an illegal act; someone who breaks the law
Example
The young offender was sentenced to community service.
その若い犯罪者はコミュニティサービスを命じられました。
C1 noun ɔːrˈdiːl

ordeal

厳しい試練
Meaning
A physical or mental painful experience that must be endured
Example
Surviving the wilderness was a tough ordeal for them.
荒野で生き残ることは彼らにとって大変な試練でした。
B2 noun /ˌɑb.zɚˈveɪ.ʃən/

Observation

観察
Meaning
the action of watching something carefully; a comment or remark
Example
The scientist made careful observations of the experiment.
科学者は実験を慎重に観察しました。
B2 adjective /ˈɒnɡəʊɪŋ/

ongoing

進行中
Meaning
continuing; still in progress
Example
The ongoing project will finish next month.
進行中のプロジェクトは来月終了します。
A2 modal verb /ɔːt/

ought

べき
Meaning
Used to indicate duty, correctness, or moral obligation.
Example
You ought to respect your elders.
あなたは年長者を尊敬すべきです。
A1 adjective /əʊˈkeɪ/

okay

大丈夫
Meaning
used to express agreement or acceptance
Example
It's okay to leave early today.
今日は早く帰るのは大丈夫です。
C1 noun /ˈaʊtˌɡroʊθ/

outgrowth

成長
Meaning
something that grows out of something else; a natural development or result
Example
The new policy was an outgrowth of years of debate.
新しい政策は数年の議論の成長でした。
C1 noun /oʊθ/

Oath

誓い
Meaning
a solemn promise or declaration; a sworn statement
Example
The doctor took an oath to help patients.
医師は患者を助けることを誓いました。
C2 noun /ˈɔːrdʒi/

orgy

乱行
Meaning
A wild party involving excessive indulgence, especially of a sexual nature.
Example
The novel described a scandalous orgy in a wealthy mansion.
その小説は、裕福な邸宅でのスキャンダラスな乱行を描いています。
C1 verb /aʊst/

oust

追放する
Meaning
To remove someone from a position or place of power or authority.
Example
The rebels ousted the dictator from power.
反乱者は独裁者を権力から追い出しました。
B2 noun /əˈfens/

Offence

違反; 犯罪
Meaning
a breach of law or rule; an annoyance or resentment
Example
Stealing is a serious offence punishable by law.
窃盗は法律で罰せられる重大な違反です。
C2 noun /ˈoʊpiət/

opiate

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.
C1 noun ˌɒb.səˈlɛs.əns

obsolescence

陳腐化
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.
テクノロジーの急速な進歩は古いデバイスの陳腐化を引き起こします。
B2 adjective ˌɒp.ərˈeɪ.ʃən.əl

operational

運用可能
Meaning
In working order; ready for use.
Example
The space project will be operational by 2025.
宇宙計画は2025年までに運用可能になります。
C1 adjective /əbˈtjuːs/

Obtuse

鈍い; 理解が遅い; 愚か
Meaning
annoyingly insensitive or slow to understand; lacking in intelligence or perception
Example
He was being deliberately obtuse about the instructions.
彼は指示に関して意図的に鈍かった。
B2 adjective + noun ˈɒptɪməl ˈtempərətʃər

optimal temperature

最適温度
Meaning
The best or most favorable temperature for a particular purpose
Example
Winter provides optimal temperature for farming.
冬は農業に最適な温度を提供します。
B2 verb /ɒpt/

opt

選ぶ
Meaning
to choose or decide to do something instead of something else
Example
Many students opt to study abroad for better opportunities.
多くの学生がより良い機会のために海外で学ぶことを選択します。
C1 verb /ˌoʊvərˈriːtʃ/

overreach

過剰な努力
Meaning
to go beyond what is proper, acceptable, or achievable; to overextend
Example
The politician overreached by making promises he couldn't keep.
その政治家は約束を守れなかったことで過剰な努力をしました。
B1 noun /ˌɒp.əˈtjuː.nə.ti/

opportunity

チャンス
Meaning
A favorable chance or set of circumstances that makes it possible to do something.
Example
She seized the opportunity to study abroad.
彼女は海外で勉強するチャンスをつかんだ。
B2 noun /ˈaʊt.breɪk/

Out-break

発生
Meaning
a sudden occurrence or eruption of something, especially disease or violence
Example
The outbreak of flu affected many students in the school.
インフルエンザの流行は学校の多くの生徒に影響を与えた。
C2 noun ˌɒbfəsˈkeɪʃən

obfuscation

難解化, 混乱
Meaning
The action of making something obscure, unclear, or unintelligible.
Example
The obfuscation of the data made it difficult to interpret.
データの難解化により、解釈が困難になりました。
B2 noun /ˈaʊt.kʌm/

Outcome

結果; 結末;
Meaning
the result or consequence of an action or situation; the final product
Example
The outcome of the election surprised everyone.
選挙の結果は皆を驚かせました。
A1 verb /ˈoʊpən/

open

開ける
Meaning
to move something so as to allow access; to begin
Example
Please open the door for me.
ドアを開けてください。
C1 adjective /əbˈstrʌk.tɪv/

Obstructive

妨害的な
Meaning
deliberately creating difficulties or preventing progress; hindering or blocking something
Example
The obstructive policies hindered economic growth.
妨害的な政策は経済成長を阻害した。
C1 noun /ˈɔːrθədɑːksi/

orthodoxy

正統
Meaning
traditional or generally accepted beliefs and practices
Example
The religious leader defended the orthodoxy of the faith.
宗教指導者は信仰の正統性を守った。
C1 verb /ˈɒs.ɪ.leɪt/

oscillate

二つの点または状態の間で前後に動くまたは揺れる
Meaning
To swing or move back and forth between two points or states
Example
The stock market tends to oscillate during uncertain times.
株式市場は不確実な時期に振動しがちです。
C2 noun /ˈɒbsɪkwiːz/

obsequies

葬儀儀式
Meaning
Funeral rites or ceremonies.
Example
The obsequies for the late leader drew thousands of mourners.
故リーダーの葬儀儀式には、数千人の弔問客が集まりました。
B2 verb əbˈzɜːrvd

observed

祝う
Meaning
To celebrate or keep a religious or other festival.
Example
The day is observed annually to raise awareness.
その日は毎年意識を高めるために祝われます。
C1 noun /ˌɑːpərˈtuːnɪst/

opportunist

機会主義者
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.
彼は常に自分の利益を第一に考える機会主義者として見られています。
A2 noun /ˈɔr.dər/

Order

命令; 順序
Meaning
a command or instruction; the arrangement of things following a particular sequence
Example
The teacher gave an order to sit down quietly.
教師は静かに座るよう命じました。
C1 noun /ˈəʊ.nəs/

onus

責任
Meaning
A duty or responsibility, especially a heavy one.
Example
The onus is on the government to provide relief to the victims.
犠牲者に支援を提供する責任は政府にあります。
A1 pronoun /aʊərz/

ours

私たちの
Meaning
belonging to or associated with us
Example
This victory is ours.
この勝利は私たちのものです。
C2 noun /oʊˈbeɪsəns/

obeisance

敬意
Meaning
A gesture of respect such as a bow or curtsy.
Example
They bowed in obeisance to the king.
彼らは王に対して敬意を示すためにお辞儀をした。
B2 noun /ˈɔːɡən/

organ

臓器
Meaning
a part of the body that performs a specific function
Example
The heart is an important organ in the human body.
心臓は人間の体の重要な臓器です。
C2 adjective /ɒˈstɛnsɪv/

ostensive

明示的
Meaning
clearly demonstrative or pointing out; explicitly shown
Example
The teacher gave an ostensive example to clarify the concept.
先生はその概念を明確にするために、明示的な例を示しました。
B1 noun /ˈɑp.ʃən/

Option

オプション
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.
自宅またはオフィスから仕事をするオプションがあります。
C2 verb /ˈɑːskjʊleɪt/

osculate

キスする
Meaning
To kiss.
Example
They osculated under the mistletoe during the party.
彼らはパーティーの時にヤドリギの下でキスをしました。
B2 noun /əbˈzɜːvər/

observer

観察者
Meaning
a person who watches or notices something
Example
The observer took notes during the meeting.
観察者は会議中にメモを取った。
C2 adjective /ˈɑːbdjʊrət/

obdurate

頑固
Meaning
Stubbornly refusing to change one's opinion or course of action.
Example
He remained obdurate despite everyone's pleas.
彼は皆の懇願にもかかわらず、頑固なままでした。
B2 noun /oʊˈbiː.di.əns/

Obedience

服従
Meaning
compliance with an order, request, or law; submission to authority
Example
Children should show obedience to their parents.
子供たちは両親に従うべきです。
A2 verb /ˈɔːfər/

offer

申し出る
Meaning
to present something for acceptance or rejection; to propose
Example
She offered to help with the project.
彼女はプロジェクトを手伝うと申し出た。
B2 noun oʊˈbiː.sə.t̬i

obesity

肥満
Meaning
The condition of being grossly fat or overweight.
Example
Obesity increases the risk of diabetes and heart disease.
肥満は糖尿病と心臓病のリスクを高めます。
B1 verb /əbˈzɜːrv/

observe

観察する
Meaning
to watch carefully; to notice or perceive something
Example
Scientists observe the behavior of animals in the wild.
科学者たちは野生動物の行動を観察します。
A1 adjective /ˈɔːr.ɪndʒ/

Orange

オレンジ色
Meaning
having a color between red and yellow like that of a ripe orange fruit
Example
The orange sunset painted the sky magnificently.
オレンジ色の夕日は空を素晴らしく彩った。
C2 noun /ˈɔːfəl/

offal

内臓
Meaning
the internal organs and entrails of an animal used as food; waste parts
Example
The butcher prepared sausages using pork offal.
肉屋は豚の臓物を使ってソーセージを作った。
C1 noun /ɒpˈtɒmɪtrɪst/

optometrist

オプトメトリスト
Meaning
A healthcare professional who examines eyes and prescribes corrective lenses.
Example
The optometrist prescribed new glasses for her.
オプトメトリストは彼女に新しい眼鏡を処方しました。
C1 noun /ˈoʊvərˌsiːər/

overseer

監督者
Meaning
a person who supervises work or workers; a manager
Example
The overseer made sure the workers followed safety rules.
監督者は、労働者が安全規則を守っていることを確認しました。
A1 verb, adjective /oʊn/

own

所有する
Meaning
to possess something; belonging to oneself
Example
She owns a beautiful house in the city.
彼女は市内に美しい家を持っています。
B2 noun ɔːˈɡæn.ɪk fuːdz

organic foods

オーガニック食品
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.
オーガニック食品は加工食品よりも健康的です。
C2 noun /oʊf/

Oaf

不器用で愚かな、無神経な人
Meaning
a clumsy, stupid, or insensitive person
Example
Don't be such an oaf - handle the dishes carefully!
そんなオーフにならないで – お皿は気をつけて洗って！
A1 adjective/adverb /ˈoʊnli/

only

唯一
Meaning
without others; solely
Example
He is the only person who knows the secret.
彼はその秘密を知っている唯一の人です。
C1 adjective ˈɒptɪmaɪzd

optimized

最適化, 改善, より効率的
Meaning
Made as fully perfect, functional, or effective as possible; improved to achieve maximum efficiency.
Example
The system has been optimized for faster performance.
システムはより速いパフォーマンスのために最適化されました。
B2 adjective /ˌɑːp.təˈmɪs.tɪk/

optimistic

楽観的
Meaning
hopeful and confident about the future
Example
She is optimistic about the success of her new project.
彼女は新しいプロジェクトの成功に楽観的です。
A1 preposition /ʌv/

of

の
Meaning
expressing the relationship between a part and a whole
Example
The book is on the table, in front of the window.
本はテーブルの上にあり、窓の前にあります。
B2 adjective /ˌɔːɡənaɪˈzeɪʃənəl/

organizational

組織的
Meaning
relating to the structure or arrangement of a company or group
Example
He works on improving the organizational structure of the company.
彼は会社の組織構造を改善するために働いています。
A2 noun /ˈoʊpənɪŋ/

opening

開店
Meaning
an act or instance of beginning something
Example
The opening of the new store was a huge success.
新しい店のオープニングは大成功でした。
C2 verb /əbˈvɜːrt/

obvert

反転する
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.
先生は生徒たちに練習のためにその声明をオブバートするように頼みました。
C1 adjective /ˈɔːrdɪnəl/

ordinal

順序数
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.
'第三'の順序数は、順番での位置を示します。
C2 adjective /ˌoʊpəˈlɛsənt/

opalescent

オパール色の
Meaning
showing or reflecting a milky, iridescent light like an opal
Example
The opalescent sky glowed with shades of pink and blue.
オパレッセントな空はピンクと青の色合いで輝いていた。
B2 noun /ˌaʊtˈsaɪdə(r)/

outsider

アウトサイダー
Meaning
a person who is not accepted as a member of a particular group or community
Example
As a new student, she often felt like an outsider at school.
新しい学生として、彼女は学校でよくアウトサイダーのように感じていました。
C1 noun /ˈɒktəɡən/

octagon

八角形
Meaning
A polygon with eight sides and eight angles.
Example
The stop sign is shaped like an octagon.
ストップサインは八角形をしています。
C1 verb /ˌaʊtˈweɪ/

outweigh

より重要である
Meaning
To be more important, valuable, or significant than something else.
Example
The benefits of the new policy outweigh the risks.
新しい政策の利益はリスクを上回っています。
B2 adjective /aʊtˈreɪdʒəs/

outrageous

ショッキング
Meaning
Shockingly bad or excessive; very unusual or amusing.
Example
The comedian told an outrageous joke.
コメディアンはショッキングなジョークを言いました。
B2 adjective /ˈaʊtˌɡoʊɪŋ/

outgoing

社交的
Meaning
Friendly and sociable; inclined to mix with others.
Example
He is an outgoing person who loves meeting new people.
彼は新しい人々と会うのが好きな社交的な人です。
B2 adjective, verb /əbˈskjʊr/

obscure

不明確
Meaning
Not clearly expressed or understood; to make something difficult to see or understand.
Example
The meaning of the poem was obscure to most readers.
詩の意味はほとんどの読者には不明確でした。
B2 verb /ˌoʊvərˈiːt/

overeat

幸福
Meaning
To eat more food than the body needs.
Example
She tends to overeat when she is stressed.
彼女は賞を受け取ったとき、喜びを隠すことができませんでした。
B2 noun /ˈaʊtskɜːrts/

outskirts

都市の郊外
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.
彼らは静かな生活を求めて都市の郊外に引っ越しました。
C1 adjective /ˌɔː.riˈen.təl/

Oriental

東アジアの国々に関連する; 東方
Meaning
relating to the countries of East Asia; eastern
Example
The museum has a beautiful collection of oriental art.
博物館には美しいオリエンタルアートのコレクションがあります。
C1 verb /ˌoʊvərˈʃædoʊ/

overshadow

覆い隠す
Meaning
to appear more important or significant than something else, reducing its impact
Example
The scandal overshadowed his achievements.
スキャンダルは彼の業績を影にしました。
C1 adjective /ˈɔːrθədɑːks/

orthodox

Meaning
conforming to traditional beliefs or practices
Example
He comes from a very orthodox family.
C1 verb /ˈɒfsɛt/

offset

相殺
Meaning
To counterbalance or compensate for something.
Example
The company's losses were offset by gains in other departments.
会社の損失は他の部門での利益で相殺されました。
C2 noun /ˌɒpəˈrɛtə/

operetta

軽いオペラ
Meaning
a short opera with light and humorous themes
Example
The theater staged a famous operetta by Gilbert and Sullivan.
劇場はギルバートとサリヴァンの有名な軽いオペラを上演しました。
C1 adjective /ˌaʊt ən ˈaʊt/

out-and-out

完全な
Meaning
complete; absolute; used to emphasize something extreme
Example
The speech was an out-and-out lie.
そのスピーチは完全な嘘だった。
C1 verb /ˌoʊvərˈθroʊ/

overthrow

幸せ
Meaning
To remove a leader or government from power, often by force.
Example
The rebels planned to overthrow the corrupt regime.
彼女は賞を受け取ったとき、幸せを隠すことができなかった。
B2 verb /ˌoʊvərˈduː/

overdo

やりすぎる
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.
初日はジムで運動をやりすぎないでください。
A2 noun /ˈɒm.lət/

Omelet

オムレツ
Meaning
a dish made from beaten eggs cooked in a frying pan and often folded around a filling
Example
She made a cheese omelet for breakfast.
彼女は朝食にチーズオムレツを作った。
B2 noun /ɒdz/

odds

確率
Meaning
the likelihood or probability of something happening; chances for or against something
Example
The odds of winning the lottery are very low.
宝くじに当選する確率は非常に低いです。
C2 noun /oʊˈbleɪʃən/

oblation

奉納
Meaning
a religious offering, especially of bread or wine to God
Example
The priest placed the oblation on the altar during the ceremony.
司祭は儀式の間に祭壇に奉納を置きました。
B1 noun /ˈɔr.ə.ʒɪn/

Origin

起源
Meaning
the point or place where something begins, arises, or is derived; the source
Example
Scientists are studying the origin of the universe.
科学者たちは宇宙の起源を研究しています。
B2 adverb /ˈɒdli/

oddly

奇妙に
Meaning
in a strange or unusual way; unexpectedly
Example
Oddly, he didn’t seem upset by the bad news.
奇妙に、彼は悪い知らせにも動揺していなかった。
B2 noun /ˌɔː.ri.enˈteɪ.ʃən/

orientation

オリエンテーション
Meaning
the process of becoming familiar with a new situation or environment
Example
The company provides an orientation for all new employees.
会社はすべての新しい従業員にオリエンテーションを提供します。
C2 noun /ˈɒlɪv brɑːntʃ/

olive-branch

オリーブの枝
Meaning
A symbol of peace or reconciliation; an offer to end conflict.
Example
He extended an olive-branch to his rival after years of hostility.
彼は長年の敵対後、ライバルにオリーブの枝を差し出した。
C2 noun /əbˈstɛtrɪks/

obstetrics

産科
Meaning
The branch of medicine dealing with childbirth and care of women giving birth.
Example
She is studying obstetrics to become a specialist in childbirth.
彼女は産科を学んで、出産専門医になろうとしている。
B2 noun ˈəʊnəʃɪp

ownership

所有権
Meaning
The act, state, or right of possessing something; legal title to something.
Example
Ownership of resources was crucial.
資源の所有権は重要でした。
C1 verb /ˌoʊvərˈruːl/

overrule

却下する
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.
裁判官は弁護側の異議を却下した。
A1 pronoun /aʊər/

our

私たちの
Meaning
belonging to or associated with the speaker and one or more other people
Example
This is our house.
これは私たちの家です。
C1 adjective /ˌoʊvərˈbɛrɪŋ/

overbearing

押しつけがましい
Meaning
unpleasantly or arrogantly domineering
Example
His overbearing attitude made everyone uncomfortable.
彼の押しつけがましい態度は、みんなを不快にさせた。
C1 adjective /oʊˈbiːs/

obese

肥満
Meaning
Extremely overweight; having an excessive amount of body fat.
Example
The doctor advised the obese patient to adopt a healthier lifestyle.
医者は肥満患者に健康的な生活様式を採用するように勧めました。
A2 noun /ˈɒpərə/

opera

オペラ
Meaning
a dramatic performance in which the actors sing most of their lines
Example
We watched a beautiful opera at the theater last night.
昨晩、劇場で美しいオペラを観ました。
A2 adverb /ˈɒbviəsli/

obviously

明らかに
Meaning
in a way that is easily perceived or understood; clearly
Example
Obviously, he didn’t read the instructions.
もちろん、彼は指示を読まなかった。