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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。
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。
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。
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。
C2 verb /ˈɑːbdʒərˌɡeɪt/

objurgate

厳しく叱る
Meaning
to scold or rebuke severely
Example
The teacher objurgated the student for being dishonest.
先生は不正直な生徒を厳しく叱った。
A2 preposition /ˈɒntu/

onto

上に
Meaning
moving to a position on the surface of something
Example
She jumped onto the table to get the book.
彼女は本を取るためにテーブルの上に飛び乗った。
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。
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。
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.
B1 verb /əˈkɜːr/

occur

発生する
Meaning
to happen or take place; to be found or present
Example
The accident occurred at the intersection during rush hour.
事故はラッシュアワーの交差点で発生しました。
C1 adjective /ˈɑp.ər.ə.tɪv/

Operative

作動中の; 効力を持つ; 仕事をしている; 操作可能な;
Meaning
Functioning; in effect; working; active;
Example
The new safety protocols became operative immediately after the accident.
新しい安全プロトコルは事故後すぐに作動しました。
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。
C2 noun /ˌɔːrnɪˈθɑːlədʒi/

ornithology

鳥類学
Meaning
the scientific study of birds
Example
She pursued ornithology to understand the migration patterns of birds.
彼女は鳥の移動パターンを理解するためにオルニソロジーを追求しました。
B2 verb /oʊˈmɪt/

omit

省略する
Meaning
to leave out or exclude; to fail to include something
Example
Please don't omit any important details from your report.
レポートから重要な詳細を省略しないでください。
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。
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。
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 noun /ˈəʊpəs/

opus

創作作品
Meaning
A creative work, especially a large and important piece of music or art.
Example
The composer considered the symphony his greatest opus.
作曲家は交響曲を自分の最も偉大な創作作品と見なしていました。
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 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。
B1 adjective /əˈbiː.di.ənt/

Obedient

従順な
Meaning
willing to comply with orders or instructions; submissive
Example
The obedient student always follows the teacher's instructions.
従順な生徒はいつも先生の指示に従う。
C1 verb ˈɔːr.kɪ.streɪt

orchestrate

調整する
Meaning
To plan or coordinate the elements of (a situation) to produce a desired effect, especially surreptitiously.
Example
He skillfully orchestrated the entire event.
彼は巧妙に全体のイベントを調整しました。
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。
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。
B1 noun ˈɒk.sɪ.dʒən

oxygen

酸素。無色無臭の気体で、生命に不可欠な成分です。
Meaning
A colorless, odorless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air.
Example
Oxygen is vital for life.
酸素は生命にとって不可欠です。
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 /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 /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。
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。
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。
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。
C1 verb /əbˈstrʌkt/

obstruct

妨げる
Meaning
to block or hinder progress; to prevent or impede movement
Example
The fallen tree obstructed the road for several hours.
倒れた木が数時間道路をふさぎました。
B2 verb /ˌoʊvərˈkʌm/

overcome

克服する
Meaning
To succeed in dealing with a problem or difficulty.
Example
You can overcome procrastination with planning.
計画を立てて先延ばしを克服できます。
C2 adjective /ˌɔːfˈkiː/

off-key

外れた音
Meaning
out of tune; not in accordance with expected standards
Example
The singer was slightly off-key during the performance.
歌手はパフォーマンス中に少し外れた音だった。
C2 noun /ˌɒn.əˌmæt.əˈpiː.ə/

onomatopoeia

オノマトペ
Meaning
The formation of a word from a sound associated with what is named.
Example
The word 'buzz' is an example of onomatopoeia.
'バズ'という言葉はオノマトペの一例です。
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。
C1 noun ˈaʊt.sɔːr.sɪŋ

outsourcing

アウトソーシング
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.
多くの企業はコスト削減のためにアウトソーシングを利用しています。
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。
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。
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。
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 /əˈblɪɡ.ə.tɔː.ri/

obligatory

義務的
Meaning
Required by a legal, moral, or other rule; compulsory.
Example
Wearing a seatbelt is obligatory in most countries.
ほとんどの国でシートベルトを着用することは義務です。
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。
B2 noun /ˈaʊtˌskɜːrt/

outskirt

郊外
Meaning
the outer edge or border of a town or city
Example
They built a new factory on the outskirts of the city.
彼らは街の郊外に新しい工場を建てました。
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 verb /ˈɑːbvieɪt/

obviate

排除する
Meaning
To remove a need or difficulty; to prevent or avoid something.
Example
This new system obviates the need for manual data entry.
この新しいシステムは手動データ入力の必要性を排除します。
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。
C1 adjective /ˌəʊ.vərˈɑː.tʃɪŋ/

overarching

全体的な, 包括的な, 包み込む
Meaning
Comprehensive or all-embracing; forming an arch over something.
Example
The overarching theme of the book is human resilience.
その本の大きなテーマは人間の回復力です。
C1 adjective /ˌaʊtˈlændɪʃ/

outlandish

奇妙
Meaning
Looking or sounding bizarre or unfamiliar; strange.
Example
He wore an outlandish costume to the festival.
彼は祭りに奇妙な衣装を着ていました。
B1 noun /ˌɒpəˈreɪʃən/

operation

手術
Meaning
an act or process of functioning or operating
Example
The hospital performed a successful operation.
病院は成功した手術を行いました。
B2 verb /ˌoʊvərˈwɛlm/

overwhelm

Meaning
to overpower someone emotionally or physically; to be too much to handle
Example
She was overwhelmed with gratitude after receiving the help.
B2 noun /ˈɔɪ.stər/

Oyster

オイスター
Meaning
a type of shellfish that can be eaten and sometimes contains pearls
Example
She ordered fresh oysters at the seafood restaurant.
彼女はシーフードレストランで新鮮なオイスターを注文しました。
B2 adverb /ˈoʊpənli/

Openly

率直に; 公然と
Meaning
in a frank and honest way; without concealment; publicly
Example
She spoke openly about her struggles with mental health.
彼女はメンタルヘルスの問題についてオープンに話した。
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。
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。
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。
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。
A1 noun /ɒkˈtoʊbər/

october

10月
Meaning
the tenth month of the year in the Gregorian calendar
Example
The weather becomes cooler in October.
10月になると天気が涼しくなります。
B2 verb /əˈpoʊz/

oppose

反対する
Meaning
to disagree with or resist; to act against
Example
Many citizens oppose the new tax policy.
多くの市民が新しい税制政策に反対しています。
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。
C2 verb /ˈɑːblɪˌɡeɪt/

obligate

強制する
Meaning
to bind legally or morally; to compel someone to do something
Example
The contract obligates the company to provide timely service.
契約は会社にタイムリーなサービスを提供することを義務付けます。
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。
C1 noun /ˈɒptɪks/

optics

光学
Meaning
The branch of physics dealing with light and vision.
Example
She studied optics to understand how lenses work.
彼女はレンズがどのように機能するかを理解するために光学を学びました。
C1 adjective /aʊtˈmoʊdɪd/

outmoded

時代遅れ
Meaning
No longer in fashion or useful; outdated.
Example
That old computer is completely outmoded.
その古いコンピューターは完全に時代遅れです。
B2 noun /ˌɒpəˈzɪʃən/

opposition

反対
Meaning
the action of opposing or resisting something
Example
The opposition to the new law was strong.
新しい法律に対する反対は強かった。
C2 noun /ˈoʊ.vər.let/

Overlet

ベッドパッド
Meaning
a thin mattress or pad placed over a bed for additional comfort
Example
The overlet makes the bed more comfortable to sleep on.
オーバーレットはベッドをより快適にして眠りやすくします。
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 /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。
B1 adjective /ˌoʊvərˈsiːz/

overseas

海外
Meaning
in or to a foreign country across the sea
Example
He went overseas for higher education.
彼は高等教育のために海外に行った。
C1 noun /əˈpreʃ.ən/

Oppression

抑圧; 虐待; 圧政;
Meaning
cruel or unjust treatment or exercise of authority; the state of being subject to harsh treatment
Example
The people fought against political oppression.
人々は政治的な抑圧に反対して戦った。
B2 noun /əbˈdʒek.ʃən/

Objection

異議; 反対; 抗議;
Meaning
an expression of disagreement or disapproval; a reason for disagreeing
Example
The lawyer raised an objection during the trial.
弁護士は裁判中に異議を唱えました。
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.
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。
C1 adjective /ˌəʊvərˈstɪmjʊˌleɪtɪd/

overstimulated

Meaning
Excessively excited or aroused, overwhelmed by too much stimulus.
Example
Overstimulated minds can lead to burnout and decreased productivity.
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 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 /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。
C1 noun ˌɒk.sɪˈdeɪ.ʃən

oxidation

酸化
Meaning
A chemical reaction that involves the combination of a substance with oxygen, often causing deterioration.
Example
Oxidation causes metal surfaces to weaken.
酸化は金属表面を弱めます。
B2 adverb /ˌoʊvərˈnaɪt/

Overnight

一晩で; 突然; 非常に速く
Meaning
during the night; suddenly; very quickly
Example
The city was transformed overnight.
街は一晩で変わった。
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。
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。
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。
B1 noun /ˈɑː.lɪv/

Olive

オリーブ
Meaning
a small oval fruit with a hard pit, typically green or black, used for eating or making oil
Example
Olive oil is considered one of the healthiest cooking oils available.
オリーブオイルは、最も健康的な料理用オイルの一つと見なされています。
B2 verb /ˌoʊvərˈpeɪ/

overpay

過剰に支払う
Meaning
To pay more than is necessary or reasonable.
Example
She realized she had overpaid for the concert tickets.
彼女はコンサートのチケットに多く支払ったことに気づきました。
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。
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。
C1 adverb /ˈaʊtwədli/

Outwardly

外見上; 表面的に;
Meaning
on the surface; externally; in appearance
Example
Outwardly, he seemed calm, but inside he was nervous.
外見上は落ち着いて見えましたが、内心では緊張していました。
C1 noun /ˈoʊ.mən/

Omen

未来の良いまたは悪い運命の兆し
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.
多くの人々は、黒猫が道を横切ることを悪いオーメンだと考えています。
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。
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。
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。
C2 noun /ˈɒb.stɪ.nə.si/

obstinacy

頑固
Meaning
Stubborn refusal to change one's opinion or chosen course of action, despite attempts to persuade one to do so.
Example
His obstinacy made negotiations difficult.
彼の頑固さは交渉を難しくしました。
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。
C2 noun /ˈɒksɪdənt/

occident

西洋
Meaning
The countries of the West, especially Europe and America.
Example
The Occident has a long history of philosophical thought.
西洋には長い哲学的思考の歴史があります。
C2 noun /ˈɔːrdnəns/

ordnance

軍需品
Meaning
Military supplies including weapons, ammunition, and combat equipment.
Example
The army stored ordnance in a secure facility outside the city.
軍隊は都市外の安全な施設に軍需品を保管していた。
B2 adjective /ˈɒp.tɪ.məl/

optimal

最適、最良
Meaning
Best or most favorable; the most effective under particular conditions.
Example
The optimal temperature for plant growth is around 25°C.
植物の成長に最適な温度は約25°Cです。
C1 adjective /əˈprɛs.ɪv/

Oppressive

抑圧的
Meaning
Harsh and authoritarian; overwhelming; causing distress; tyrannical;
Example
The oppressive heat made it difficult to work outside during the summer.
厳しい暑さは夏の間外で働くのを難しくした。
B2 adjective /əˈfen.sɪv/

Offensive

攻撃的な; 侮辱的な; 攻撃的
Meaning
causing displeasure or resentment; insulting; aggressive
Example
His offensive remarks hurt everyone's feelings.
彼の攻撃的な発言は、全員の気持ちを傷つけました。
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。
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。
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。
C2 noun /əˈblɪkwɪti/

obliquity

歪み
Meaning
Deviation from moral or usual conduct; indirectness or lack of straightforwardness.
Example
The politician was criticized for the obliquity of his answers.
その政治家は、彼の答えの歪みについて批判された。
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。
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。
C2 noun /ˌɔːrnɪˈθɒlədʒɪst/

ornithologist

鳥類学者
Meaning
a scientist who studies birds
Example
The ornithologist spent years studying migratory birds.
そのオルニソロジストは渡り鳥を研究するために何年も費やしました。
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 /ˈɔr.fən/

Orphan

孤児
Meaning
a child whose parents are dead; someone without protective support
Example
The orphan was adopted by a loving family.
その孤児は愛情深い家族に養子として迎えられました。
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 verb /ˈɒkjʊpaɪ/

occupy

占める / 占有する / 居住する
Meaning
to take up space or time; to live or work in a place
Example
The new family will occupy the house next month.
新しい家族は来月その家に入居する予定です。
A2 noun /ˈoʊ.ʃən/

ocean

海洋
Meaning
A very large expanse of sea, especially the main areas of sea between continents.
Example
The ocean covers more than 70% of the Earth's surface.
海洋は地球の表面の70％以上を覆っています。
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。
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。
B1 noun /ˌɑk.jəˈpeɪ.ʃən/

Occupation

職業; 仕事; 占領
Meaning
a job or profession; the action of taking control of a place
Example
Teaching is her chosen occupation.
教えることは彼女の選んだ職業です。
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 adjective /ˈɔːrθədɑːks/

orthodox

Meaning
conforming to traditional beliefs or practices
Example
He comes from a very orthodox family.
C2 adjective /ˈoʊ.pən ˈhɑrt.ɪd/

Open-hearted

オープンハート; 寛大で誠実; 心温かく受け入れる;
Meaning
Kind and generous; sincere and honest; warmly receptive;
Example
She welcomed the strangers with an open-hearted smile and invited them for dinner.
彼女は見知らぬ人々を心温かい笑顔で迎え、夕食に招待した。
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。
A2 noun /ˈoʊ.nər/

Owner

所有者
Meaning
a person who owns something; someone who has legal possession of property
Example
The owner of the restaurant greeted us warmly.
レストランの所有者は私たちを温かく迎え入れてくれました。
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。
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。