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B1 adjective /əˈfɪʃəl/

official

公式
Meaning
relating to or connected with an authority or public office
Example
He is the official spokesperson for the company.
彼は会社の公式なスポークスマンです。
C2 adjective /əˈrækjələr/

oracular

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

Ominous

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

Odorous

芳香のある; 香り高い
Meaning
having a strong smell; fragrant; aromatic
Example
The garden was filled with odorous flowers.
庭は芳香のある花で満たされていた。
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。
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。
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。
B1 noun ˌɒpəˈtjuːnɪtiz

opportunities

チャンス
Meaning
A set of circumstances that makes it possible to do something; chances for advancement or success.
Example
Opportunities for jobs decreased.
仕事のチャンスが減少しました。
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。
B2 noun /ˌɑb.lɪˈɡeɪ.ʃən/

Obligation

義務
Meaning
a duty or commitment; something that must be done legally or morally
Example
Parents have an obligation to care for their children.
親は子供の世話をする義務がある。
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。
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。
B2 noun /ˈɒkjʊpənt/

occupant

乗客
Meaning
A person who resides in or is present in a house, vehicle, seat, or place.
Example
The car had three occupants at the time of the accident.
事故の時、車には三人の乗客がいました。
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 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。
C1 adjective /ˌoʊvərˈrɔt/

overwrought

興奮した / 過度に緊張した
Meaning
extremely agitated or nervous; excessively elaborate
Example
She was too overwrought to speak clearly after the accident.
事故後、彼女は興奮しすぎて、はっきりと話すことができなかった。
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。
C2 noun /ˈɔɪl.mən/

Oilman

石油業者
Meaning
a person who works in the oil industry; someone who sells oil or petroleum products
Example
The oilman discovered a new oil field in the desert.
オイルマンは砂漠で新しい油田を発見した。
B1 verb অকার্স

occurs

起こる
Meaning
Happens or takes place, especially as a result of something.
Example
Snowfall occurs in regions with freezing temperatures.
雪は氷点下の温度を持つ地域で起こります。
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。
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。
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。
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。
C2 adjective /əˈprəʊ.bri.əs/

opprobrious

侮辱的な
Meaning
Expressing strong criticism or scorn.
Example
He made opprobrious remarks about his opponent.
彼は対戦相手に対して侮辱的な発言をしました。
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。
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。
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。
B2 noun ɔːˈɡæn.ɪk fuːdz

organic foods

オーガニック食品
Meaning
Food produced without the use of chemicals such as artificial pesticides, fertilizers, or other artificial agents.
Example
Organic foods are healthier than processed foods.
オーガニック食品は加工食品よりも健康的です。
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。
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.
A2 modal verb /ɔːt/

ought

べき
Meaning
Used to indicate duty, correctness, or moral obligation.
Example
You ought to respect your elders.
あなたは年長者を尊敬すべきです。
B2 noun /oʊk/

oak

オークの木
Meaning
a large tree that produces acorns and has strong, hard wood
Example
The old oak tree provided shade for the entire yard.
古いオークの木は庭全体に日陰を提供しました。
C1 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 /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。
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。
C2 noun ˈɒpjʊləns

opulence

富裕
Meaning
Great wealth or luxuriousness.
Example
The opulence of the mansion was evident in its ornate furnishings.
豪邸の富裕さはその華やかな家具に明らかでした。
C2 adjective /ˌoʊdəˈrɪfərəs/

odoriferous

芳香のある
Meaning
having or giving off a smell, especially a strong or pleasant one
Example
The garden was filled with odoriferous flowers.
庭は芳香のある花でいっぱいでした。
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。
B2 verb /əˈfend/

offend

侮辱する
Meaning
to cause displeasure or resentment; to hurt someone's feelings
Example
His rude comments offended many people at the meeting.
彼の無礼なコメントは会議で多くの人々を怒らせました。
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。
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。
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 /ˌɑːpərˈtuːnɪst/

opportunist

機会主義者
Meaning
A person who takes advantage of situations for personal gain, often disregarding principles.
Example
He is seen as an opportunist who always puts his interests first.
彼は常に自分の利益を第一に考える機会主義者として見られています。
A2 noun /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。
C1 noun /ˈɑːlɪˌɡɑːrki/

oligarchy

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

occult

オカルト
Meaning
Relating to mysterious, supernatural, or magical powers and practices.
Example
She had always been fascinated by the occult and its hidden knowledge.
彼女は常にオカルトとその隠された知識に魅了されていた。
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。
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。
B2 noun /əˈfens/

Offence

違反; 犯罪
Meaning
a breach of law or rule; an annoyance or resentment
Example
Stealing is a serious offence punishable by law.
窃盗は法律で罰せられる重大な違反です。
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。
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 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。
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。
B2 noun /ˈaʊtˌfɪt/

outfit

衣装
Meaning
A set of clothes worn together, often for a particular occasion.
Example
She wore a beautiful outfit to the party.
彼女はパーティーに美しい衣装を着て行った。
C1 adjective /ˌaʊtˈspoʊkən/

Outspoken

率直
Meaning
frank; speaking directly
Example
She is known for being outspoken about social issues.
彼女は社会問題について率直に話すことで知られています。
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。
C1 noun /əbˈdʒɛktər/

objector

反対者
Meaning
a person who expresses opposition or disapproval to something
Example
The objector raised his concerns during the town meeting.
反対者は市議会の会議中に自分の懸念を表明しました。
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。
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。
C1 noun /ˈaʊtpoʊst/

outpost

前哨基地
Meaning
A small military camp or position at some distance from the main force, used especially as a guard.
Example
The soldiers were stationed at a remote outpost.
兵士たちは遠隔地の前哨基地に配置されました。
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。
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。
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 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 /ˈɔːrɪndʒfɪn ˈleɪbiːoʊ/

Orangefin labeo

オレンジフィンラベオ
Meaning
a freshwater fish species native to South Asian rivers, commonly found in Bangladesh and India
Example
The orangefin labeo is an important food fish in Bangladesh.
オレンジフィンラベオはバングラデシュで重要な食用魚です。
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。
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。
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 /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。
A1 adverb /aʊt/

out

外
Meaning
moving or appearing away from the inside or center; not at home or present
Example
He stepped out of the room quietly.
彼は静かに部屋を出ました。
B2 noun /ˌɔː.ri.enˈteɪ.ʃən/

orientation

オリエンテーション
Meaning
the process of becoming familiar with a new situation or environment
Example
The company provides an orientation for all new employees.
会社はすべての新しい従業員にオリエンテーションを提供します。
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。
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。
B2 noun /ɒdz/

odds

確率
Meaning
the likelihood or probability of something happening; chances for or against something
Example
The odds of winning the lottery are very low.
宝くじに当選する確率は非常に低いです。
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。
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。
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。
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。
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。
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。
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 noun /ˌɑːpərˈtuːnɪzəm/

opportunism

機会主義
Meaning
The practice of taking advantage of opportunities regardless of principles or ethics.
Example
His decision was driven by opportunism, not values.
彼の決定は、価値観ではなくオポチュニズムに動機づけられていました。
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 /ˈɒfərɪŋ/

offering

オファリング
Meaning
something that is given, especially as a gift or contribution
Example
The company’s latest offering is an eco-friendly car.
会社の最新のオファリングは、エコフレンドリーな車です。
B2 adverb /ˈaʊtraɪt/

Outright

直接に; 完全に; ためらわずに
Meaning
completely; directly; without reservation or concealment
Example
She rejected the proposal outright.
彼女はその提案を直接拒否した。
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。
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。
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 verb /ˌoʊvərˈstraɪd/

overstride

大きな一歩で越える
Meaning
To stride over something; to step across with long steps.
Example
He managed to overstride the narrow stream with ease.
彼は狭い小川を簡単に越えることができました。
C1 noun /ˈoʊvərˌsiːər/

overseer

監督者
Meaning
a person who supervises work or workers; a manager
Example
The overseer made sure the workers followed safety rules.
監督者は、労働者が安全規則を守っていることを確認しました。
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 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。
C2 adjective /əbˈtruːsɪv/

obtrusive

目障りな
Meaning
noticeable in an unpleasant or unwelcome way; intrusive
Example
The advertisement was so obtrusive that it ruined the user’s experience.
その広告はあまりにも目立ちすぎて、ユーザーの体験を台無しにしました。
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 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。
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。
A1 adverb /ɔːf/

off

オフ
Meaning
away from a place, position, or time; not functioning
Example
He turned off the light before leaving the room.
彼は部屋を出る前に電気をオフにしました。
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。
C1 noun /ˈɑd.ɪ.ti/

Oddity

珍奇な現象
Meaning
something that is strange or unusual; a peculiar trait
Example
His habit of sleeping standing up was considered an oddity.
彼の立って寝る習慣は珍奇な現象と見なされていました。
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。
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。
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。
B1 verb /oʊ/

owe

借りがある
Meaning
to be under obligation to pay or repay; to be indebted
Example
I owe my success to my parents' support.
私は両親の支援のおかげで成功しました。
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。
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 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。
C1 noun /ˈɔːr.ə.tɔːr.i/

oratory

弁論術
Meaning
The art of public speaking; skilled and confident delivery of speeches to an audience.
Example
His exceptional oratory skills won him the debate competition.
彼の卓越した弁論術は、ディベートコンペティションで彼に勝利をもたらしました。
B2 noun /ˈaʊt.kʌm/

Outcome

結果; 結末;
Meaning
the result or consequence of an action or situation; the final product
Example
The outcome of the election surprised everyone.
選挙の結果は皆を驚かせました。
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。
C2 noun /ˌɔːrdɪˈneɪʃən/

ordination

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