overwhelming
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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。
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。
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。
C1 noun /ˈaʊtriːtʃ/

outreach

支援拡大
Meaning
The act of providing services or support to people who might not otherwise have access to them.
Example
The charity launched a new outreach program for the homeless.
チャリティはホームレスのために新しい支援拡大プログラムを開始しました。
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。
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 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。
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 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。
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。
B1 noun /əˈkeɪ.ʒən/

Occasion

機会; 特別な出来事
Meaning
a particular time or instance of an event; a special celebration
Example
Their wedding was a joyous occasion.
彼らの結婚式は喜ばしい機会でした。
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。
A1 pronoun, noun, adjective /wʌn/

one

一
Meaning
the number equivalent to the sum of zero and one; a single person or thing
Example
Only one student answered the question.
ただ一人の学生が質問に答えました。
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 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。
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。
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 adjective /ɒmˈnɪv.ər.əs/

Omnivorous

雑食性
Meaning
eating both plants and animals; feeding on various kinds of food
Example
Bears are omnivorous animals that eat both plants and meat.
クマは雑食性の動物で、植物と肉を食べます。
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。
A2 noun /ˈɒf.ɪs/

office

オフィス
Meaning
a room or building where people work, usually at desks
Example
She left the office early to attend a family event.
彼女は家族のイベントに出席するために早くオフィスを出ました。
C1 verb /aʊtˈlɪv/

outlive

より長生きする
Meaning
to live longer than someone or something else
Example
She outlived all her siblings.
彼女はすべての兄弟姉妹より長生きしました。
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。
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 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 adjective /ˌɒstɛnˈteɪʃəs/

ostentatious

見せびらかしの
Meaning
Characterized by a showy or pretentious display intended to impress others.
Example
He wore an ostentatious gold chain to the party.
彼はパーティーで見せびらかしの金のチェーンをしていました。
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。
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。
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。
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 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.
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 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。
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。
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。
C1 noun /ˌɒbstəˈtrɪʃən/

obstetrician

産科医
Meaning
A doctor specializing in pregnancy, childbirth, and women's reproductive health.
Example
The obstetrician monitored the mother’s health throughout the pregnancy.
産科医は妊娠中の母親の健康を監視しました。
B2 noun /ˈaʊtɪŋ/

outing

お出かけ
Meaning
a short trip or excursion, often for leisure or enjoyment
Example
They had a lovely outing at the beach last weekend.
彼らは先週末、ビーチで素晴らしいお出かけをしました。
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。
A2 noun /əˈlɪmpɪks/

olympics

オリンピック競技大会
Meaning
an international sports competition held every four years with athletes from many countries
Example
The Olympics bring athletes from all over the world together.
オリンピックは世界中のアスリートを一堂に集めます。
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 /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。
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。
C1 noun /əˈkɜr.əns/

Occurrence

出来事
Meaning
an instance or event of something happening; the fact of occurring
Example
The occurrence of earthquakes is common in this region.
この地域では地震の出来事が一般的です。
B2 noun /ˈɔːrɡənaɪzər/

organizer

主催者
Meaning
a person who arranges or coordinates activities, events, or groups; a tool or item used to keep things in order
Example
She worked as the main organizer of the international conference.
彼女は国際会議の主要な主催者だった。
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。
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。
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。
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 /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 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 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 adjective /ˈɒptɪk/

optic

視覚の
Meaning
Relating to the eye or vision.
Example
The optic nerve carries signals from the eye to the brain.
視神経は目から脳に信号を伝達します。
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。
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。
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。
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。
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。
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。
C1 noun /ˌəʊvərɪksˌplɔɪˈteɪʃən/

overexploitation

過剰搾取
Meaning
The unsustainable use of natural resources at a rate that exceeds their ability to regenerate, leading to depletion and environmental degradation.
Example
Overexploitation of natural resources leads to environmental degradation.
自然資源の過剰搾取は環境の悪化を引き起こします。
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。
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 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。
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。
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。
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。
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 adjective /ˌaʊt əv ðə ˈweɪ/

out-of-the-way

人里離れた場所
Meaning
remote or unusual; not in a convenient or usual location
Example
They stayed in an out-of-the-way village.
彼らは人里離れた村に滞在しました。
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 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 verb /ˌoʊvərˈliːp/

overleap

飛び越える
Meaning
To jump over something; to omit or disregard something.
Example
He managed to overleap the fence easily.
彼は簡単にフェンスを飛び越えました。
C1 adjective /ˈɔːrθədɑːks/

orthodox

Meaning
conforming to traditional beliefs or practices
Example
He comes from a very orthodox family.
A1 interjection /oʊ/

oh

オー
Meaning
used to express surprise, realization, or understanding
Example
Oh, I didn't know you were here!
オー、あなたがここにいるとは思わなかった！
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。
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。
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。
C1 verb /ˌaʊtˈstrɪp/

outstrip

凌駕する
Meaning
To go faster or do better than someone or something; to surpass.
Example
The company outstripped its competitors in sales last year.
その会社は昨年、販売で競合他社を上回った。
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。
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。
C2 verb /ˌaʊtməˈnuːvər/

outmaneuver

巧妙に出し抜く
Meaning
to gain an advantage over an opponent by skillful or clever action
Example
The smaller company managed to outmaneuver its larger rival.
小さな会社は大きな競争相手を巧妙に出し抜くことに成功した。
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。
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。
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 noun /ɔːˈræŋ.ʊˌtæŋ/

Orang-Outang

オランウータン
Meaning
a large arboreal ape with long reddish hair, long arms, and hooked hands and feet, native to Borneo and Sumatra
Example
The orangutan swings gracefully through the forest canopy.
オランウータンは森の樹冠を優雅に渡ります。
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。
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。
A1 noun/adjective/adverb /ˌaʊtˈsaɪd/

outside

外
Meaning
the external part or surface of something; beyond the boundary
Example
Children were playing outside in the yard.
子供たちは庭で外で遊んでいました。
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。
C2 noun /ˈɒbsɪkwi/

obsequy

葬儀
Meaning
A funeral rite, usually used in plural form obsequies.
Example
The village gathered for the obsequy of their beloved teacher.
村人たちは、愛する教師の葬儀のために集まりました。
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。
B2 noun /ˌɒb.zəˈveɪ.ʃənz/

observations

観察
Meaning
The action or process of observing something carefully.
Example
Observations of distant galaxies provide new insights.
遠くの銀河の観察は新たな洞察を提供します。
C1 noun /oʊˈveɪʃən/

ovation

拍手
Meaning
an enthusiastic show of approval, especially by clapping hands
Example
The actor received a standing ovation after his performance.
俳優はパフォーマンス後にスタンディングオベーションを受けました。
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。
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 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。
C2 adjective /əbˈstrɛpərəs/

obstreperous

騒がしくて制御が難しい
Meaning
Noisy and difficult to control.
Example
The obstreperous students disrupted the class.
騒がしい学生たちが授業を妨害した。
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 /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。
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。
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 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。
C2 noun /ˌɔːrəˈtɔːri.oʊ/

oratorio

宗教音楽作品
Meaning
A large-scale musical composition for orchestra, choir, and soloists, usually on a sacred theme, performed without costumes or scenery.
Example
Handel's 'Messiah' is one of the most famous oratorios ever written.
ヘンデルの『メサイア』は最も有名なオラトリオの1つです。
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。
B2 noun /ˈaʊtˌsɛt/

outset

開始
Meaning
the beginning or start of something
Example
From the outset, the project seemed ambitious but achievable.
最初から、プロジェクトは野心的だが達成可能に見えました。
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。
B1 noun əbˈdʒek.tɪv

objective

目標
Meaning
A thing aimed at or sought; a goal.
Example
The main objective is to test sustainability.
メインオブジェクティブは持続可能性をテストすることです。
C1 noun /ˈoʊvərˌtʊr/

overture

序曲 / 提案
Meaning
An introduction to something more substantial; a proposal or preliminary action.
Example
The peace overture was welcomed by both nations.
平和提案は両国によって歓迎されました。
B1 noun /ˈɒbstəkəlz/

obstacles

障害物
Meaning
Things that block one's way or prevent or hinder progress.
Example
Obstacles in life can often lead to valuable lessons.
人生の障害物はしばしば貴重な教訓に繋がる。
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。
C1 adjective /əbˈsɛsɪv/

obsessive

執着的
Meaning
Relating to or characterized by an obsession; thinking about something too much.
Example
He has an obsessive interest in cleanliness.
彼は清潔さに執着的な興味を持っています。
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 adjective /oʊˈvɜːrt/

overt

公然
Meaning
Done or shown openly; not hidden or secret.
Example
There was an overt display of hostility between the rivals.
ライバルの間に公然とした敵意の表れがあった。
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 /əˈkluːd/

occlude

閉塞する
Meaning
To block or close up an opening or passage.
Example
The pipe was occluded by mineral deposits.
パイプは鉱物の堆積物で閉塞されていました。
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。
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。
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。
C1 adjective /əbˈzɜːrvənt/

Observant

観察力のある
Meaning
quick to notice things; watchful; attentive
Example
The observant detective noticed every small detail at the crime scene.
観察力のある探偵は犯罪現場のあらゆる小さな詳細に気づきました。
B1 adjective /ˈaʊtər/

outer

外部
Meaning
situated on or toward the outside; external
Example
The outer layer of the jacket is waterproof.
ジャケットの外側の層は防水です。
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 /ˈoʊdiəm/

odium

嫌悪
Meaning
general or widespread hatred or disgust directed toward someone as a result of their actions
Example
The scandal brought public odium on the corrupt minister.
スキャンダルは腐敗した大臣に対する公衆の嫌悪を引き起こした。
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。
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。