osculate
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
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 /wʌn θɜːd/

one-third

三分の一
Meaning
one part of something that is divided into three equal parts
Example
One-third of the class was absent today.
クラスの三分の一が今日は欠席でした。
A1 adverb /ˈɔːfən/

often

しばしば
Meaning
frequently, many times
Example
I often visit my grandparents on weekends.
私は週末にしばしば祖父母を訪れます。
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。
C1 verb /ˈɔːstrəˌsaɪz/

ostracize

追放する
Meaning
to exclude someone from a group or society; to banish or shun
Example
After the scandal, he was ostracized by his former colleagues.
スキャンダル後、彼は元同僚に追放された。
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。
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。
C1 noun /ˈɑːdəsi/

odyssey

長い旅
Meaning
a long, adventurous journey; a series of experiences
Example
Her career has been an odyssey of challenges and achievements.
彼女のキャリアは挑戦と成果の長い旅でした。
B1 adjective /əˈrɪdʒ.ɪ.nəl/

Original

元の; 基本的な; 本物の
Meaning
first; fundamental; primary; authentic
Example
This is the original document, not a copy.
これはオリジナルの文書で、コピーではありません。
C2 verb /ˈɒsɪfaɪ/

ossify

骨化する
Meaning
to turn into bone or become rigid and inflexible
Example
With age, some tissues tend to ossify.
年を重ねると、一部の組織が骨化する傾向があります。
C1 noun /ˈɔːrkɪd/

Orchid

オーキッド
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.
窓辺の白いオーキッドは何ヶ月も咲き続けました。
C2 noun /ˈɔːrɪndʒfɪn ˈleɪbiːoʊ/

Orangefin labeo

オレンジフィンラベオ
Meaning
a freshwater fish species native to South Asian rivers, commonly found in Bangladesh and India
Example
The orangefin labeo is an important food fish in Bangladesh.
オレンジフィンラベオはバングラデシュで重要な食用魚です。
C2 noun /oʊliˈændər/

Oleander

オレアンダー
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.
美しいオレアンダーの花が庭で咲いていましたが、その毒性に関わらず。
A2 adjective /ˈɔː.dɪ.nər.i/

Ordinary

普通の; 一般的な; 特別ではない
Meaning
normal; usual; not special
Example
It was just an ordinary day at the office.
それはオフィスでのただの普通の日でした。
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。
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。
C2 adjective /ˌoʊvərˈwiːnɪŋ/

overweening

過度に傲慢な
Meaning
excessively arrogant or prideful
Example
His overweening pride cost him many friends.
彼の過度の誇りは多くの友人を失わせました。
C2 adjective /ˈɒf.biːt/

offbeat

風変わり
Meaning
Unusual, unconventional, or different from the norm.
Example
She has a very offbeat sense of humor.
彼女はとても風変わりなユーモアを持っています。
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 /ˈoʊ.vər ɡroʊθ/

Over growth

過剰成長
Meaning
excessive growth beyond normal size; too much development or expansion
Example
The overgrowth of weeds made the garden look untidy.
雑草の過剰な繁茂が庭を乱雑に見せた。
C2 noun /ˈɒn.rʌʃ/

onrush

突発的な流れ
Meaning
A sudden powerful forward or downward rush or flow.
Example
The onrush of water swept away the bridge.
水の突発的な流れが橋を流しました。
C2 verb /aʊtˈraɪd/

outride

追い越す
Meaning
to ride faster, farther, or better than someone else
Example
The young rider managed to outride his competitors in the race.
若いライダーはレースで競技者たちを追い越しました。
C2 adjective /ˈɔːrnəri/

ornery

気難しい
Meaning
bad-tempered and combative; stubborn
Example
The ornery old man refused to leave his chair.
その気難しい老人は椅子を離れようとしませんでした。
C1 adjective əʊˈpeɪk

opaque

不透明, 理解しにくい
Meaning
Not able to be seen through; not transparent; difficult to understand.
Example
The glass was too opaque to see through.
そのガラスは不透明すぎて、透けて見えませんでした。
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。
B2 noun /ˈaʊtˌfɪt/

outfit

衣装
Meaning
A set of clothes worn together, often for a particular occasion.
Example
She wore a beautiful outfit to the party.
彼女はパーティーに美しい衣装を着て行った。
A2 adverb; noun /ˌaʊtˈdɔːrz/

outdoors

屋外で
Meaning
outside a building; the natural environment outside
Example
We spent the whole afternoon outdoors enjoying the fresh air.
私たちは午後ずっと屋外で新鮮な空気を楽しみました。
C1 adjective /ˌoʊvərˈbloʊn/

overblown

誇張された
Meaning
excessively exaggerated or inflated
Example
The controversy was overblown by the media.
メディアによって論争は誇張されました。
A2 noun /ˈʌn.jən/

Onion

玉ねぎ
Meaning
a round vegetable with a strong taste and smell, made up of many layers
Example
I need to chop some onions for the curry recipe.
カレーのレシピのためにいくつか玉ねぎを切る必要があります。
B2 noun, verb /ˈaʊtlɔː/

outlaw

Meaning
as a noun: a person who breaks the law and lives outside its protection; as a verb: to make something illegal
Example
The government decided to outlaw the harmful practice.
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。
C2 adjective /əˈprəʊ.bri.əs/

opprobrious

侮辱的な
Meaning
Expressing strong criticism or scorn.
Example
He made opprobrious remarks about his opponent.
彼は対戦相手に対して侮辱的な発言をしました。
C1 noun /ˈɒn.slɔːt/

onslaught

猛攻
Meaning
A fierce or destructive attack.
Example
The village faced an onslaught of enemy forces.
その村は敵軍の猛攻に直面しました。
C2 adjective /əˈrækjələr/

oracular

神託のような
Meaning
Resembling an oracle; giving wise, mysterious, or prophetic statements
Example
Her oracular words left the audience deep in thought.
彼女の神託のような言葉は、観客を深く考えさせた。
C1 noun /əbˈstrʌkʃən/

obstruction

障害
Meaning
Something that blocks or gets in the way; the action of obstructing.
Example
There was an obstruction on the railway track.
鉄道の線路に障害がありました。
A1 preposition /ɒn/

on

上
Meaning
physically in contact with and supported by a surface
Example
The book is on the table.
本はテーブルの上にあります。
B1 adjective /ˌoʊld ˈfæʃənd/

old-fashioned

昔風の
Meaning
not modern; belonging to an earlier time
Example
He still wears an old-fashioned hat.
彼は今でも昔風の帽子をかぶっています。
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 adjective /ˈɒm.ɪ.nəs/

Ominous

不吉な; 脅威の
Meaning
giving the impression that something bad will happen; threatening; foreboding
Example
The dark clouds looked ominous before the storm.
嵐の前に、暗い雲は不吉に見えました。
C2 noun ˈɒpjʊləns

opulence

富裕
Meaning
Great wealth or luxuriousness.
Example
The opulence of the mansion was evident in its ornate furnishings.
豪邸の富裕さはその華やかな家具に明らかでした。
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 əˈlɪm.pɪk ɡeɪmz

Olympic Games

オリンピック競技大会
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.
オリンピック競技大会は世界のトップアスリートを集めます。
C2 noun /ˈɔɪl.mən/

Oilman

石油業者
Meaning
a person who works in the oil industry; someone who sells oil or petroleum products
Example
The oilman discovered a new oil field in the desert.
オイルマンは砂漠で新しい油田を発見した。
C2 adjective /ˈoʊ.pən ˈhæn.dɪd/

Open-handed

寛大な; 自由な
Meaning
Generous; liberal; giving freely;
Example
He is very open-handed with his money and always helps those in need.
彼は自分の金に非常に寛大で、いつも困っている人々を助けています。
A2 adjective /ˈɑp.ə.zɪt/

Opposite

反対の; 完全に異なる; 向かい合っている; 逆の;
Meaning
Contrary; completely different; facing each other; reverse;
Example
They have opposite views on politics but remain good friends.
彼らは政治に関して対立した見解を持っていますが、良い友達のままです。
C1 adjective əˈblɪv.i.əs

oblivious

無自覚
Meaning
Being completely unaware of surrounding events.
Example
He was oblivious to the noise around him while reading.
彼は読書中に周りの騒音に全く無自覚だった。
B2 noun /ˈaʊtˌbreɪk/

outbreak

発生
Meaning
a sudden start or occurrence of something unpleasant, like disease or violence
Example
There was an outbreak of flu in the city.
街でインフルエンザが発生した。
C2 noun /ˌɒktədʒəˈnɛəriən/

octogenarian

80歳代の人
Meaning
A person who is between 80 and 89 years old.
Example
The octogenarian still jogs every morning to stay healthy.
そのオクトジェネリアンは毎朝健康を維持するためにジョギングをしています。
B2 noun /ˈoʊ.dər/

Odour

臭い
Meaning
a distinctive smell, especially an unpleasant one
Example
The odour of fresh bread filled the kitchen.
新鮮なパンの臭いがキッチンに広がった。
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。
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。
C1 noun /ˈɒf.sprɪŋ/

offspring

子孫
Meaning
a person's child or children; an animal's young
Example
The bird carefully fed its offspring.
その鳥は注意深く自分の子孫に餌を与えました。
B2 adjective ɔːrˈɡæn.ɪk

organic

有機
Meaning
Produced or involving production without the use of chemical fertilizers, pesticides, or other artificial agents.
Example
Organic farming improves soil health and reduces pollution.
有機農業は土壌の健康を改善し、汚染を減少させます。
C2 noun /ɒkˈteɪvoʊ/

octavo

オクターヴォ (紙を8つに折りたたんで作られた本のサイズ)
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.
古い図書館にはシェイクスピアの珍しいオクターヴォ版がありました。
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。
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。
C1 noun /oʊˈbɪt.ʃu.er.i/

Obituary

訃報
Meaning
a notice of someone's death published in a newspaper; biographical account of deceased person
Example
The newspaper published his obituary yesterday.
新聞は昨日彼の訃報を掲載しました。
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。
B2 noun /əbˈsɛʃən/

obsession

執着
Meaning
An idea, thought, or concern that continually preoccupies or intrudes on a person's mind.
Example
His obsession with success drove him to work day and night.
成功への執着が彼を昼夜働かせた。
C2 noun /ˈɒkjʊlɪst/

oculist

眼科医
Meaning
An old-fashioned term for an eye doctor or ophthalmologist.
Example
The village oculist was known for treating various eye diseases.
村のオキュリストは、さまざまな目の病気を治療することで知られていました。
B2 noun /ˈoʊvərpæs/

overpass

高架橋
Meaning
A bridge that carries one road or railway over another.
Example
The new overpass reduced traffic congestion in the city.
新しい高架橋は市内の交通渋滞を減らしました。
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。
A2 pronoun /aʊərˈsɛlvz/

ourselves

私たち自身
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.
私たちは他の人を助ける前に、自分たち自身を助けるべきです。
A2 adjective /ˈaʊtdɔːr/

outdoor

アウトドア
Meaning
situated, existing, or done outside a building
Example
We planned an outdoor picnic for the weekend.
週末のためにアウトドアピクニックを計画しました。
C2 adjective /ɑːlˈfæktəri/

olfactory

Meaning
Relating to the sense of smell.
Example
The perfume activated her olfactory nerves immediately.
B2 noun /ˈɔr.fən.ɪʒ/

Orphanage

孤児院
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.
チャリティーはホームレスの子供たちのために新しい孤児院を建てました。
C1 noun /ˈɔr.i.ənt/

Orient

東洋、特に東アジアの国々
Meaning
the East, especially countries of eastern Asia; to determine one's position or direction
Example
Many spices come from the Orient.
多くの香辛料がオリエントから来ています。
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。
C1 noun /ˌoʊvərprəˈdʌkʃən/

overproduction

過剰生産
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.
経済危機は商品の過剰生産によって引き起こされた。
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。
B1 noun ˌɔː.ɡən.aɪˈzeɪ.ʃən

organization

組織
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.
その組織は2024年に公式に開設されました。
B1 noun /aʊl/

Owl

フクロウ
Meaning
a nocturnal bird of prey with large eyes and a hooked beak
Example
The owl hooted softly in the darkness of the forest.
フクロウは森の暗闇で静かに鳴いた。
C1 verb /ˌaʊtˈstrɛtʃ/

outstretch

外に伸ばす
Meaning
To extend or stretch something outward.
Example
He outstretched his hand to help her up.
彼は彼女を助けるために手を差し出した。
C1 noun /ɔːr/

Oar

オール
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.
彼はオールを水に浸し、ボートを前に進めた。
C2 adjective /ˈoʊ.kən/

oaken

オーク材で作られた
Meaning
made of or resembling oak wood
Example
The villagers gathered around the oaken table in the hall.
村人たちはホールの中のオーク材のテーブルの周りに集まりました。
B1 adverb /əˈrɪdʒɪnəli/

originally

元々
Meaning
in the beginning, at first
Example
Originally, she wanted to be a doctor.
元々、彼女は医者になりたかった。
B2 adjective /ˈɔː.də.li/

Orderly

整然とした; 系統的な; 平和的な
Meaning
well-organized; systematic; peaceful
Example
Please keep your desk orderly and clean.
デスクを整然とした状態できれいに保ってください。
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。
A2 adjective /əˈlɪmpɪk/

olympic

オリンピック
Meaning
related to the Olympic Games, a major international sporting event
Example
She trained hard to compete in the Olympic Games.
彼女はオリンピックに出場するために一生懸命トレーニングをしました。
C2 noun /ˌɔːrdɪˈneɪʃən/

ordination

任命式
Meaning
The ceremony of conferring holy orders or official religious authority.
Example
The church held a special service for the ordination of new priests.
教会は新しい神父の任命のために特別なサービスを行いました。
C1 noun /ˈɑːlɪˌɡɑːrki/

oligarchy

寡頭政治
Meaning
A small group of people having control of a country, organization, or institution.
Example
The nation was ruled by a wealthy oligarchy that controlled all resources.
その国は裕福なオリガーキーによって支配され、すべての資源を支配していました。
C1 noun /ɒpˈtɒmətri/

optometry

視力検査学
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.
彼女は大学でオプトメトリーを学び、眼科専門医になりました。
C1 verb /ˈɒp.tɪ.maɪz/

optimize

最適化する
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.
会社はサプライチェーンの最適化に取り組んでいます。
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。
C1 noun /oʊˈmɪʃ.ən/

Omission

省略; 除外
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.
リストから彼の名前を省略することは意図的でした。
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。
C2 noun /ˈoʊɡər/

ogre

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.
C1 noun /ˈoʊvərˌtoʊn/

overtone

微妙な意味
Meaning
A subtle quality, implication, or additional meaning beyond the obvious.
Example
His speech had political overtones that were hard to ignore.
彼のスピーチには無視できない政治的なニュアンスが含まれていました。
C1 adjective /ˈəʊnərəs/

onerous

重い
Meaning
involving a great deal of effort, difficulty, or burden
Example
Fulfilling the contract proved to be an onerous task for the company.
契約を履行することは会社にとって負担の大きい仕事だと証明された。
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 adjective /ˌoʊvərˈwɛlmɪŋ/

overwhelming

圧倒的
Meaning
Very intense; overpowering.
Example
Large tasks can feel overwhelming.
大きな仕事は圧倒的に感じることがあります。
B2 noun/verb /ˈoʊvərˌdoʊs/

overdose

過剰摂取
Meaning
An excessive and dangerous amount of a drug; to take too much of a substance.
Example
He was rushed to the hospital after a drug overdose.
薬物の過剰摂取で病院に運ばれました。
B2 verb /ˌoʊvərˈlʊk/

overlook

見落とす
Meaning
to fail to notice or consider something; to have a view from above
Example
It's easy to overlook small details when you're in a hurry.
急いでいると、細かい点を見落とすことがあります。
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。
B2 verb /ˌoʊvərˈloʊd/

overload

過負荷
Meaning
to load with too much weight or cargo; to give too much work or information
Example
Don't overload the washing machine or it might break down.
洗濯機をオーバーロードしないでください、壊れるかもしれません。
B1 noun /ˈɔːfɪsər/

officer

警官
Meaning
a person in a position of authority, especially in law enforcement
Example
The officer gave him a ticket for speeding.
警官はスピード違反で彼にチケットを渡した。
C2 noun /ˈɑːbəlɪsk/

obelisk

オベリスク
Meaning
A tall, four-sided, narrow tapering monument with a pyramid-shaped top.
Example
The ancient Egyptians built obelisks to honor their gods.
古代エジプト人は神々を讃えるためにオベリスクを建てました。
B1 noun /ˈɑb.stə.kəl/

Obstacle

障害物
Meaning
something that blocks or makes progress difficult; a barrier
Example
Bad weather was the main obstacle to our journey.
悪天候が私たちの旅行の最大の障害物でした。
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。
B1 verb /ˈɒpəreɪt/

operate

操作する
Meaning
to function; to control or manage; to perform surgery
Example
The surgeon will operate on the patient tomorrow.
外科医は明日患者を手術します。
C1 verb /ˌaʊtˈduː/

outdo

超える
Meaning
To do better than someone else; to surpass.
Example
She always tries to outdo her classmates in exams.
彼女は試験でクラスメートを常に超えようとします。
C1 noun /ˈɒfʃuːt/

offshoot

分岐
Meaning
A branch or result that develops from something larger or more important.
Example
The startup was an offshoot of a major tech company.
そのスタートアップは大手テクノロジー企業からの分岐でした。
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 noun /oʊk/

oak

オークの木
Meaning
a large tree that produces acorns and has strong, hard wood
Example
The old oak tree provided shade for the entire yard.
古いオークの木は庭全体に日陰を提供しました。
C1 adjective /əbˈnɒkʃəs/

Obnoxious

不快な
Meaning
extremely unpleasant; offensive; annoying
Example
His obnoxious behavior at the party annoyed everyone.
彼のパーティーでの非常に不快な振る舞いは、皆を困らせた。
C2 adjective /əbˈsiːkwɪəs/

obsequious

お世辞
Meaning
Excessively obedient or attentive in a servile way.
Example
The waiter gave an obsequious bow to every customer.
ウェイターは各顧客にお世辞のようなお辞儀をしました。
B1 verb /ˈɔːrɡənaɪz/

organize

整理する
Meaning
to arrange systematically; to plan and coordinate
Example
She organized a surprise party for her friend.
彼女は友達のためにサプライズパーティーを企画した。
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。
C1 noun /ˈɑn.set/

Onset

開始; 始まり
Meaning
the beginning or early stages of something; the start of a medical condition
Example
The onset of winter brought heavy snowfall.
冬の開始は大雪をもたらしました。
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 /ˌɑːsɪˈleɪʃən/

oscillation

振動
Meaning
The movement back and forth at a regular speed.
Example
The oscillation of the pendulum controls the clock.
振り子の振動が時計を制御します。
C1 verb /əˈfɪʃieɪt/

officiate

執り行う
Meaning
To perform official duties, especially in a ceremony or as a referee.
Example
The priest will officiate the wedding ceremony.
司祭が結婚式を司る。
B2 adjective /ˈɒp.ʃən.əl/

Optional

任意
Meaning
not compulsory; left to choice
Example
Wearing a tie is optional for this event.
このイベントではネクタイの着用は任意です。
B2 adjective /ˈɔɪl.i/

Oily

油っぽい; 油で覆われた; 脂っこい
Meaning
covered with oil; containing oil; greasy
Example
Her oily skin needs special care.
彼女の油っぽい肌は特別なケアが必要です。
B2 noun /ˈɒfərɪŋ/

offering

オファリング
Meaning
something that is given, especially as a gift or contribution
Example
The company’s latest offering is an eco-friendly car.
会社の最新のオファリングは、エコフレンドリーな車です。
C2 adjective /əˈfɪʃəs/

officious

干渉的な
Meaning
Excessively eager to offer unwanted help or advice; meddlesome.
Example
The officious guard kept interrupting the visitors with unnecessary instructions.
その干渉的な警備員は訪問者に不必要な指示で何度も中断させた。
C1 adjective /ˈaʊt.kɑːst/

Outcast

社会的に排除された人
Meaning
rejected by society; excluded person
Example
He felt like an outcast in his new school.
彼は新しい学校でアウトキャストのように感じていた。
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。
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。
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。