offal
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 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 adjective /əˈbliːk/

Oblique

斜め; 対角線; 間接的または回避的
Meaning
slanting; diagonal; indirect or evasive
Example
The artist drew an oblique line across the canvas.
アーティストはキャンバスに斜めの線を描いた。
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。
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 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。
C1 adjective /ˌəʊvərˈstɪmjʊˌleɪtɪd/

overstimulated

Meaning
Excessively excited or aroused, overwhelmed by too much stimulus.
Example
Overstimulated minds can lead to burnout and decreased productivity.
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。
B2 adjective /ˌfæʃ.ənd/

Outdated

時代遅れ
Meaning
obsolete; no longer current
Example
This computer software is completely outdated.
このソフトウェアは完全に時代遅れです。
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。
B2 noun /ˈɒpəreɪtər/

operator

オペレーター
Meaning
a person who operates equipment, a business, or controls something
Example
The machine operator ensured that everything ran smoothly.
機械オペレーターは、すべてがスムーズに動作することを確認しました。
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。
B2 noun /ˈaʊt.laɪn/

Outline

アウトライン; 概要; 計画
Meaning
a general description or plan showing the essential features of something; the main points
Example
The teacher provided an outline of the course syllabus.
先生はコースのアウトラインを提供しました。
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。
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。
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。
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 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。
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。
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 /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。
C1 adjective /ɒˈstɛnsəbl/

ostensible

見せかけの
Meaning
stated or appearing to be true, but not necessarily so
Example
His ostensible reason for leaving was illness, but many doubted it.
彼の出発の見せかけの理由は病気だったが、多くの人がそれを疑っていた。
B1 adjective /ˌoʊvərˈweɪt/

overweight

過体重
Meaning
heavier than is considered healthy or normal
Example
The doctor advised him to lose weight as he was overweight.
医者は体重を減らすようにアドバイスしました、なぜなら彼は過体重だったからです。
B2 noun /əˈfɛns/

offense

犯罪
Meaning
an illegal act; a crime
Example
The offense was committed in broad daylight.
その罪は昼間に犯されました。
C2 adjective /ɔːrˈθɑːɡənl/

orthogonal

直交
Meaning
at right angles; independent or unrelated
Example
In mathematics, two vectors are orthogonal if their dot product is zero.
数学では、2つのベクトルが直交している場合、そのドット積はゼロです。
C2 adjective /ˌɒbsəˈlɛsnt/

obsolescent

時代遅れの
Meaning
Becoming outdated or on the way to becoming obsolete.
Example
The obsolescent technology could not compete with modern devices.
時代遅れの技術は現代のデバイスには競争できなかった。
C2 noun /oʊd/

ode

オード
Meaning
a lyrical poem, often expressing praise or strong emotions
Example
The poet wrote an ode to the beauty of nature.
詩人は自然の美に対するオードを書いた。
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。
B2 noun /ˈaʊtlet/

outlet

出口
Meaning
a means by which something is released, expressed, or distributed
Example
Art is a great outlet for emotions.
アートは感情のための素晴らしい出口です。
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。
A1 adjective /oʊld/

old

古い
Meaning
having lived for a long time; not new or young
Example
He still drives his old car.
彼は今でも古い車を運転しています。
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。
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。
B2 adjective /əˈpəʊzd/

opposed

反対の
Meaning
being against or in disagreement with something
Example
She is strongly opposed to animal testing.
彼女は動物実験に強く反対しています。
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.
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 noun /ˈaʊtbɜːrst/

outburst

感情または活動の突然の爆発
Meaning
a sudden release of strong emotion or activity
Example
She had an angry outburst during the meeting.
会議中に彼女は怒りの爆発をした。
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。
C1 verb əˈblɪt.ə.reɪt

obliterate

完全に破壊する
Meaning
To destroy utterly; wipe out completely, to erase or remove something completely.
Example
The storm obliterated entire villages.
嵐は村全体を完全に破壊しました。
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！
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。
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 adjective /ˈoʊdiəs/

odious

忌まわしい
Meaning
extremely unpleasant or repulsive
Example
The dictator was remembered for his odious crimes.
その独裁者は彼の忌まわしい犯罪で記憶されました。
B1 verb /ˈɒpəreɪtɪŋ/

operating

運営する
Meaning
to control or manage the functioning of something
Example
The company has been operating in this market for five years.
その会社はこの市場で5年間運営されています。
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。
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 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。
C1 noun /əbˈzɜːvəns/

observance

遵守
Meaning
The practice of following a custom, rule, or religious law.
Example
The festival is held in observance of a centuries-old tradition.
その祭りは、数世代にわたる伝統を遵守して行われます。
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。
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。
A2 adjective/adverb /ˈɒnˌlaɪn/

online

オンライン
Meaning
connected to or available through the internet
Example
I prefer shopping online rather than going to stores.
私はお店に行くよりもオンラインで買い物をする方が好きです。
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。
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。
C2 adjective /ɑːlˈfæktəri/

olfactory

Meaning
Relating to the sense of smell.
Example
The perfume activated her olfactory nerves immediately.
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 /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。
C1 adjective /ˈɒptɪməm/

optimum

最適
Meaning
Most conducive to a favorable outcome; best.
Example
To achieve optimum results, we need to improve efficiency.
最適な結果を得るためには、効率を改善する必要があります。
A2 adjective /ɒd/

Odd

奇妙な; 異常な; 正常または予想されるものとは異なる
Meaning
strange; unusual; different from what is normal or expected
Example
That's an odd way to solve the problem.
それは問題を解決する奇妙な方法です。
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。
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 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。
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。
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。
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 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 /ɒmˈnɪp.ə.tənt/

omnipotent

全能
Meaning
Having unlimited power; able to do anything; all-powerful.
Example
In many religions, God is considered omnipotent.
多くの宗教では、神は全能だと考えられています。
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。
B2 noun /ˈaʊt.saɪ.dər/

Out-sider

アウトサイダー
Meaning
a person who does not belong to a particular group; someone not accepted by a group
Example
As an outsider, he found it difficult to understand their traditions.
アウトサイダーとして、彼は彼らの伝統を理解するのが難しいと感じました。
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 noun /ɑːks/

Ox

雄牛
Meaning
a large strong animal used for pulling heavy loads or plowing fields
Example
The farmer used an ox to plow the field.
農夫は畑を耕すために雄牛を使いました。
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。
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 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。
C1 noun /ˌɒk.sɪ.dʒɪˈneɪ.ʃən/

oxygenation

酸素供給または治療
Meaning
The process of supplying or treating with oxygen.
Example
Deep breathing exercises improve oxygenation of the body.
深呼吸の練習は身体の酸素供給を改善します。
C1 verb /ˈoʊvərˌhɔːl/

overhaul

完全な改修
Meaning
to examine thoroughly and repair or improve something that is worn or ineffective
Example
The company decided to overhaul its outdated computer system.
会社は古くなったコンピュータシステムのオーバーホールを決定した。
C2 noun /əbˈstrʌkʃənɪst/

obstructionist

Meaning
a person who deliberately delays or prevents progress by being uncooperative or oppositional
Example
The obstructionist in the committee kept delaying the decision-making process.
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 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。
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。
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 /ˈɔr.ə.tər/

Orator

演説家
Meaning
a public speaker, especially one who is eloquent or skilled in speaking
Example
The famous orator delivered an inspiring speech.
有名な演説家が感動的なスピーチを行った。
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。
C2 noun /ˈɑb.lə.kwi/

Obloquy

厳しい批判または言葉による虐待; 公共の非難
Meaning
harsh criticism or verbal abuse; strong public condemnation
Example
The politician faced obloquy after the scandal.
政治家はスキャンダルの後、厳しい批判を受けました。
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。
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。
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.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。
B2 noun ˈəʊ.və.hed

overhead

間接費
Meaning
Ongoing business expenses not directly attributable to creating a product or service.
Example
The company reduced its overhead to increase profits.
会社は利益を増やすために間接費を削減した。
C1 adjective /ɔːˈneɪt/

ornate

華やかな
Meaning
elaborately or highly decorated
Example
The palace hall was filled with ornate furniture and paintings.
宮殿のホールは華やかな家具と絵画でいっぱいだった。
C2 adjective /ˈɒfɪʃ/

offish

無愛想
Meaning
Unfriendly, distant, or reserved in manner.
Example
He seemed offish at the party and avoided most conversations.
彼はパーティーで無愛想に見え、大半の会話を避けていました。
C1 noun/verb /ˈoʊvərˌhæŋ/

overhang

突出部
Meaning
To extend outward and hang over something; a projecting part.
Example
The roof overhang provides shade in the summer.
屋根のオーバーハングは夏に日陰を提供します。
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。
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 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。
C2 noun /ˈɒrɪz(ə)n/

orison

祈り
Meaning
a prayer, especially a devout or formal one
Example
He whispered a quiet orison before going to sleep.
寝る前に静かな祈りをささやいた。
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。
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。
B2 noun /ɔːrˈɡæn.ɪk ˈfɑːr.mɪŋ/

organic farming

有機農業
Meaning
Farming method that avoids synthetic chemicals and fertilizers, using natural methods instead.
Example
Organic farming improves soil health and reduces pollution.
オーガニックファーミングは土壌の健康を改善し、汚染を減らします。
C1 noun /ˈɔr.ə.kəl/

Oracle

オラクル
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.
古代ギリシャ人はデルポイのオラクルに相談しました。
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。
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。
C1 noun /ˈɒktɪv/

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.
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。
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。
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。
B2 verb /ˌoʊvərˈteɪk/

overtake

追い越す
Meaning
to catch up with and pass someone or something; to surpass
Example
The runner managed to overtake his competitor in the final lap.
ランナーは最後の周回で競争相手を追い越しました。
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。
A1 preposition, adverb /ˈoʊvər/

over

上に
Meaning
across, on top of, or beyond
Example
The book is lying over the table.
本はテーブルの上にあります。
C1 adjective /ˌɑːpərˈtuːn/

opportune

適切な瞬間
Meaning
Happening at a suitable or convenient time.
Example
She arrived at an opportune moment to help.
彼女は助けるために適切な瞬間に到着しました。
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 /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。
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。
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。
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 /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。
B2 adverb /əˈfɪʃəli/

officially

公式に
Meaning
in a formal or authorized way
Example
The building was officially opened by the mayor.
その建物は市長によって公式に開かれました。
C1 noun /ˈɔɪntmənt/

ointment

軟膏
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.
医師は彼の腕のやけどのために軟膏を処方しました。
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。
C1 adjective ˈɒk.sɪ.də.tɪv

oxidative

酸化に関連する
Meaning
Related to or caused by oxidation, especially cellular damage from free radicals.
Example
Excess stress can lead to oxidative damage in cells.
過度のストレスは細胞に酸化的な損傷を引き起こす可能性があります。
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。
C1 noun ˈoʊʃən əˌsɪdɪfɪˈkeɪʃən

ocean acidification

海洋酸性化
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.
海洋酸性化は、大気中のCO2の吸収によって引き起こされます。
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。