obsequious
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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。
B2 noun /ˈoʊtˌmiːl/

oatmeal

オートミール
Meaning
A type of porridge made from ground oats, often eaten for breakfast.
Example
She eats a bowl of oatmeal every morning for breakfast.
彼女は毎朝、朝食にオートミールを一杯食べます。
B2 adjective /ˈaʊtˌɡoʊɪŋ/

outgoing

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

obsolescence

陳腐化
Meaning
The process of becoming obsolete or outdated and no longer used.
Example
The rapid advancement of technology leads to the obsolescence of old devices.
テクノロジーの急速な進歩は古いデバイスの陳腐化を引き起こします。
B2 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。
C1 adjective /əˈblaɪdʒɪŋ/

obliging

親切な
Meaning
Willing to help or do favors; accommodating.
Example
The staff at the hotel were very obliging and friendly.
ホテルのスタッフはとても親切で友好的でした。
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。
C2 noun /ˌɑːbdʒərˈɡeɪʃən/

objurgation

厳しい叱責
Meaning
a harsh scolding or strong rebuke
Example
His misconduct earned him a severe objurgation from the manager.
彼の不正行為はマネージャーから厳しい叱責を受けた。
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。
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。
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。
C1 adjective /ˌɒmnɪˈprezənt/

omnipresent

至る所に存在する
Meaning
(of God) present everywhere at the same time.
Example
Social media has become an omnipresent force in modern society.
ソーシャルメディアは現代社会において至る所に存在する力となりました。
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 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。
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 verb /ˈɒs.ɪ.leɪt/

oscillate

二つの点または状態の間で前後に動くまたは揺れる
Meaning
To swing or move back and forth between two points or states
Example
The stock market tends to oscillate during uncertain times.
株式市場は不確実な時期に振動しがちです。
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 /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 /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。
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。
B2 noun /ˈɔːkɪstrə/

orchestra

オーケストラ
Meaning
a large group of musicians playing different instruments together
Example
The orchestra performed beautifully at the concert.
オーケストラはコンサートで素晴らしい演奏をしました。
C1 adjective /ˌɔːrnəˈmɛntl/

ornamental

装飾的な
Meaning
Serving as decoration; decorative rather than functional.
Example
The garden was filled with ornamental plants.
庭は装飾的な植物でいっぱいだった。
B2 noun ˈɒksɪdʒən prəˈdʌkʃən

oxygen production

酸素生産
Meaning
The process of generating oxygen through photosynthesis or other means.
Example
Plants are vital for oxygen production and the maintenance of life.
植物は酸素の生産と生命の維持に不可欠です。
C1 noun ˌɒp.tɪ.maɪˈzeɪ.ʃən

optimization

最適化
Meaning
Improving processes to increase performance and efficiency.
Example
SEO optimization helps websites rank higher on search engines.
SEO最適化はウェブサイトが検索エンジンでより高いランクを獲得するのを助けます。
C1 noun /ˈoʊ.vər spɪl/

Over-spill

オーバーフロー
Meaning
the overflow of liquid from a container; excess that cannot be contained
Example
The overspill from the river flooded nearby farms.
川の溢れが近くの農場を水浸しにした。
C1 adjective ˈɒb.stɪ.nət

obstinate

頑固
Meaning
Refusing to change one's mind or accept others' advice easily.
Example
He remained obstinate despite the logical arguments.
彼は論理的な議論にもかかわらず頑固なままでいた。
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.
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 /əbˈzɜːrvətɔːri/

observatory

天文台
Meaning
A building equipped for observing astronomical or meteorological events.
Example
The observatory is open to the public on weekends.
天文台は週末に一般公開されています。
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。
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 /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。
A2 noun /ˈʌv.ən/

Oven

オーブン
Meaning
an enclosed compartment used for heating, baking, or drying food
Example
She baked cookies in the oven for thirty minutes.
彼女はオーブンで三十分間クッキーを焼きました。
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。
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。
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。
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 /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。
B2 noun /ˈɔːɡən/

organ

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

orotund

豊かで明確な声
Meaning
full, rich, and clear in sound; pompous in style
Example
The actor's orotund voice filled the theater.
俳優の豊かな声が劇場に響き渡った。
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。
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。
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。
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。
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。
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。
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 ˈaʊt.pʊt

output

生産量
Meaning
The amount of something produced by a person, machine, or industry.
Example
Climate change reduces agricultural output.
気候変動は農業の生産量を減少させます。
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。
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 /əˈprəʊ.bri.əm/

opprobrium

非難, 恥辱
Meaning
Harsh criticism or public disgrace.
Example
The scandal brought opprobrium on the politician.
スキャンダルは政治家に非難を浴びせた。
C1 verb /aʊst/

oust

追放する
Meaning
To remove someone from a position or place of power or authority.
Example
The rebels ousted the dictator from power.
反乱者は独裁者を権力から追い出しました。
C1 adjective /əbˈtjuːs/

Obtuse

鈍い; 理解が遅い; 愚か
Meaning
annoyingly insensitive or slow to understand; lacking in intelligence or perception
Example
He was being deliberately obtuse about the instructions.
彼は指示に関して意図的に鈍かった。
C2 noun /əbˈstɛtrɪks/

obstetrics

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

ozone depletion

オゾン層の減少
Meaning
The reduction in the amount of ozone in the Earth's stratosphere, leading to increased UV radiation.
Example
Ozone depletion increases UV radiation.
オゾン層の減少はUV放射線を増加させます。
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。
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 adverb /ˈəʊvəli/

overly

過度に
Meaning
to an excessive degree or extent
Example
She was overly concerned about the results.
彼女は結果について過度に心配していた。
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。
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。
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 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。
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。
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。
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。
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。
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！
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。
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 adjective /ˈɔːɡənaɪzd/

organized

組織的な
Meaning
Arranged in a systematic way, especially on a large scale.
Example
An organized approach to work increases productivity and reduces stress.
仕事に対する組織的なアプローチは、生産性を高め、ストレスを減らします。
C1 verb /uːz/

ooze

にじみ出る
Meaning
to slowly flow or leak out through small openings or pores
Example
Blood began to ooze from the small cut.
血が小さな切り傷からにじみ出た。
C2 adjective /ˈɑːsɪˌfaɪd/

ossified

骨に変わった、硬直した
Meaning
Turned into bone or become rigid; unwilling to change.
Example
The company had an ossified management structure that resisted innovation.
その会社は、革新に抵抗する硬直した管理構造を持っていました。
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 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。
C2 verb /ˈoʊɡəl/

ogle

じっと見る
Meaning
To look at someone with obvious sexual interest.
Example
He kept ogling the models on the runway.
彼はランウェイのモデルたちを見続けた。
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。
B2 noun /ˈɑp.tə.mɪst/

Optimist

楽観主義者
Meaning
a person who tends to be hopeful and confident about the future; someone who sees the good side of things
Example
As an optimist, she always believed things would improve.
楽観主義者として、彼女は常に物事が改善されると信じていました。
C1 noun əˈblɪv.i.ən

oblivion

忘却, 破壊, 消失
Meaning
The state of being unaware or unconscious of what is happening; complete forgetfulness.
Example
His name faded into oblivion over time.
彼の名前は時と共に忘却の中に消えた。
C2 noun /ɔːrˈθɑːɡrəfi/

orthography

正書法
Meaning
The conventional spelling system of a language.
Example
English orthography can be confusing for learners.
英語の正書法は学習者にとって混乱を招くことがあります。
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 /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。
A2 noun /ˈɒbdʒɪkt/

object

物体
Meaning
a thing that can be seen and touched
Example
The table is an object in the room.
テーブルは部屋の中の物体です。
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。
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 /ˌoʊpəˈlɛsəns/

opalescence

オパレスセンス
Meaning
a milky or pearly appearance of a surface like that of an opal
Example
The pearl had a gentle opalescence under the light.
パールは光の下で優しいオパレスセンスを持っていました。
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。
B1 adjective /əˈkeɪ.ʒən.əl/

Occasional

偶然の
Meaning
occurring infrequently or irregularly; happening from time to time
Example
She enjoys occasional walks in the park.
彼女は公園で偶然の散歩を楽しんでいます。
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。
C2 noun /ɒmˈnɪʃəns/

omniscience

全知
Meaning
the state of knowing everything
Example
The novel's narrator has an air of omniscience, revealing every character's thoughts.
小説の語り手は全知の空気をまとい、すべてのキャラクターの考えを明らかにしている。
C1 adverb /ˈɒp.tɪ.məl.i/

optimally

最適に
Meaning
In the most effective or efficient way possible.
Example
Tasks should be allocated optimally for maximum output.
タスクは最大の成果を上げるために最適に割り当てるべきです。
C1 adjective /ˌɒbsəˈliːt/

obsolete

時代遅れ
Meaning
No longer in use or out of date.
Example
Floppy disks are now completely obsolete.
フロッピーディスクは現在完全に時代遅れです。
C2 noun /ˈaʊtˌrɪɡər/

outrigger

安定構造
Meaning
a projecting structure on a boat, used for stability, or a boat fitted with such support
Example
The fisherman paddled his outrigger canoe across the lagoon.
漁師はアウトリガー付きのカヌーをラグーンを越えて漕ぎました。
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 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 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。
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 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。
C1 noun /ˈɔːrθədɑːksi/

orthodoxy

正統
Meaning
traditional or generally accepted beliefs and practices
Example
The religious leader defended the orthodoxy of the faith.
宗教指導者は信仰の正統性を守った。
C1 verb /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。
A1 verb /ˈoʊpən/

open

開ける
Meaning
to move something so as to allow access; to begin
Example
Please open the door for me.
ドアを開けてください。
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.
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 noun /əˌrɪʒ.əˈnæl.ə.ti/

Originality

独創性
Meaning
the quality of being novel or unusual; the ability to think independently and creatively
Example
The artist's work showed great originality and creativity.
アーティストの作品は大きな独創性と創造性を示した。
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。
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。
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。
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。
C2 adjective /ɑːlˈfæktəri/

olfactory

Meaning
Relating to the sense of smell.
Example
The perfume activated her olfactory nerves immediately.
C2 noun /ɔːˈreɪʃən/

oration

演説
Meaning
A formal speech, especially one given on a ceremonial occasion
Example
The president delivered an inspiring oration.
大統領は感動的な演説を行いました。
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。
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。
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。
C1 noun ˌoʊ.vɚˈɡreɪ.zɪŋ

overgrazing

過剰放牧
Meaning
The practice of allowing livestock to graze to the point of damaging vegetation.
Example
Overgrazing leads to soil erosion and loss of biodiversity.
過剰放牧は土壌の浸食と生物多様性の喪失を引き起こします。
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。