diffusion
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C1 noun /dɪˈfjuːʒən/

diffusion

Meaning
the spreading of something more widely or the movement of particles from high to low concentration
Example
The diffusion of information on social media is rapid.
C1 noun /dɪsˈɪntrəst/

disinterest

無関心
Meaning
lack of interest or concern
Example
His disinterest in the project was obvious.
そのプロジェクトへの無関心は明らかだった。
C1 verb /dɛlv/

delve

Meaning
To investigate deeply; to dig into a subject or area.
Example
The researcher delved into ancient manuscripts to find clues.
C1 adjective /dɪsˈpæʃənət/

dispassionate

冷静な
Meaning
not influenced by strong emotion; impartial
Example
The judge remained dispassionate throughout the trial.
裁判官は裁判全体を通して冷静さを保ちました。
C1 noun /ˈdɑːrwɪnɪzəm/

darwinism

ダーウィニズム
Meaning
the theory of biological evolution developed by Charles Darwin, emphasizing natural selection
Example
Darwinism revolutionized the way scientists understood the origin of species.
ダーウィニズムは科学者たちが種の起源を理解する方法を革命的に変えました。
C1 verb /deɪz/

daze

Meaning
to stun or confuse someone temporarily with a shock or surprise
Example
The bright lights dazed the runners as they entered the stadium.
C1 adjective /dɪˈspɪkəbl/

despicable

卑劣な
Meaning
Deserving hatred and contempt; vile or shameful.
Example
His despicable actions shocked the entire community.
彼の卑劣な行動はコミュニティ全体を驚かせました。
C1 noun /dɪˈstɔːrʃən/

distortion

歪曲、誤った提示
Meaning
the action of twisting, changing, or misrepresenting the shape, sound, or truth of something
Example
There was a distortion in the radio signal.
ラジオ信号に歪曲がありました。
C1 verb /dɪsˈpleɪs/

displace

置き換える
Meaning
to force someone or something out of their usual or original position; to replace or substitute
Example
The new technology will displace many traditional manufacturing jobs.
新しい技術は多くの伝統的な製造業の仕事を置き換えるでしょう。
C1 adjective /dɪˈskriːt/

discrete

離散的
Meaning
individually separate and distinct
Example
The course is divided into three discrete modules.
コースは3つの離散的なモジュールに分けられています。
C1 noun /doʊ/

doe

雌鹿
Meaning
a female deer, especially an adult one
Example
The doe and her fawn were grazing in the meadow.
雌鹿とその子鹿は草原で草を食べていました。
C1 verb /druːp/

droop

垂れる
Meaning
to bend or hang downward; to become weak or tired
Example
The flowers began to droop in the heat.
花は暑さで垂れ始めました。
C1 verb /ˌdɪsəˈlaʊ/

disallow

許可しない
Meaning
to refuse to allow or accept something
Example
The referee disallowed the goal for offside.
審判はオフサイドのためゴールを認めませんでした。
C1 adjective /dɪˈpreɪvd/

depraved

堕落した
Meaning
morally corrupt or wicked
Example
The film depicts the life of a depraved criminal.
その映画は堕落した犯罪者の人生を描いています。
C1 noun dɛkˈstɛr.ɪ.ti

dexterity

器用さ
Meaning
Skill in performing tasks, especially with the hands; mental skill or adroitness.
Example
His dexterity in playing the piano amazed the audience.
ピアノを弾く彼の器用さに観客は驚いた。
C1 noun /dɪˈpɑːzətɔːri/

depository

預け場所, 保管所
Meaning
a place where things are stored or deposited, especially financial assets
Example
The national depository safeguards all government bonds.
国家のデポジトリはすべての政府債券を保護しています。
C1 verb /ˈdɛprɪˌkeɪt/

deprecate

非難する
Meaning
to express disapproval of something
Example
The teacher deprecated the use of slang in academic essays.
教師は学術論文でのスラングの使用を非難しました。
C1 noun /ˈdɛsɪˌbɛl/

decibel

デシベル
Meaning
a unit used to measure the intensity of sound
Example
The noise level in the factory exceeded 90 decibels.
工場の騒音レベルは90デシベルを超えました。
C1 noun ˌdep.əˈzɪʃ.ən

deposition

堆積、何かを堆積させるプロセス
Meaning
The action of depositing something; the laying down of matter by a natural process.
Example
River deposition leads to the formation of new landmasses.
河川の堆積は新しい大陸の形成をもたらします。
C1 adjective /dɪˈmɒnstrəbl/

demonstrable

証明可能
Meaning
clearly able to be shown or proven
Example
There was demonstrable evidence that he was innocent.
彼が無罪であることを示す証明可能な証拠がありました。
C1 adjective /ˈdesələt/

Desolate

荒涼; 孤独; 不毛
Meaning
deserted; lonely; barren
Example
The abandoned village looked desolate and empty.
放棄された村は荒涼として空っぽに見えた。
C1 noun/verb /dɪsˈdeɪn/

disdain

Meaning
The feeling that someone or something is unworthy of respect; to regard with contempt.
Example
She looked at the messy room with open disdain.
C1 noun/verb /dɛnt/

dent

へこみ
Meaning
a small hollow mark on the surface of something; to make a small hollow mark
Example
The accident left a dent in the car door.
事故で車のドアにへこみが残りました。
C1 noun /ˌdɪspəˈzɪʃən/

disposition

Meaning
A person's usual attitude or temperament; arrangement or tendency.
Example
She has a cheerful disposition despite the difficulties.
C1 verb /dəˈmɛstɪkeɪt/

domesticate

家畜化する
Meaning
to tame an animal for use by humans; to adapt something for domestic use
Example
Humans domesticated dogs thousands of years ago.
人間は数千年前に犬を家畜化しました。
C1 verb /dɪˈpoʊz/

depose

Meaning
to remove someone from office or power, especially suddenly and forcefully
Example
The rebels managed to depose the dictator after years of unrest.
C1 verb /daɪˈvʌldʒ/

divulge

明らかにする
Meaning
to make known something private, secret, or previously unknown
Example
She refused to divulge the source of her information.
彼女は情報の源を明らかにすることを拒否しました。
C1 adjective /dɪˈklærətɪv/

declarative

宣言的
Meaning
relating to a statement that declares something; in grammar, a sentence that makes a statement
Example
A declarative sentence simply states a fact or opinion.
宣言的な文は、単に事実や意見を述べるものです。
C1 noun /ˌdɪsəˈbiːdiəns/

disobedience

不従順
Meaning
failure or refusal to obey rules, laws, or authority
Example
The child's disobedience worried his parents.
子供の不従順は両親を心配させました。
C1 adverb /ˈduːli/

Duly

適切に, 時間通りに
Meaning
in accordance with what is required or appropriate; at the proper time
Example
The documents were duly signed and submitted.
書類は適切に署名され、提出されました。
C1 noun dɪˈspær.ə.ti

disparity

格差
Meaning
A great difference or inequality.
Example
Disparity between countries must be reduced.
国々の間の格差は減少するべきです。
C1 verb /dɪˈdjuːs/

deduce

推測する
Meaning
to reach a conclusion by reasoning or inference
Example
From the evidence, the detective deduced that the suspect was lying.
証拠から、探偵は容疑者が嘘をついていることを推測しました。
C1 adjective /ˈdɪn.dʒi/

Dingy

汚れていて暗い; 色が鈍い
Meaning
dark and dirty; gloomy; dull in color
Example
The old building had dingy walls that needed painting.
古い建物は、塗装が必要な汚れた壁を持っていた。
C1 noun /djuːˈɛt/

duet

デュエット
Meaning
a musical performance by two singers or instrumentalists
Example
They sang a beautiful duet together on stage.
彼らはステージで一緒に美しいデュエットを歌った。
C1 adjective, noun /ˈdɛrəlɪkt/

derelict

放棄された
Meaning
in poor condition due to neglect or disuse; a homeless or neglected person
Example
The old factory stood derelict for decades.
古い工場は何十年も放置されていました。
C1 verb /drɛntʃ/

drench

びしょ濡れにする
Meaning
to make someone or something completely wet
Example
The sudden rain drenched the players on the field.
突然の雨がフィールドの選手たちをびしょ濡れにした。
C1 noun /ˌdiː.mɑːˈkeɪ.ʃən/

Demarcation

境界設定
Meaning
the action of fixing the boundary or limits of something; separation or division
Example
The demarcation between public and private land was clearly marked.
公共の土地と私有地の境界設定は明確に示されていた。
C1 adjective /ˈdɪs.ə.plɪ.ner.i/

Disciplinary

懲戒的
Meaning
relating to discipline; intended to correct behavior
Example
The company took disciplinary action against the employee.
会社は従業員に対して懲戒措置を取りました。
C1 verb /dɪsˈhɑːrtn/

dishearten

落胆させる
Meaning
to cause someone to lose determination or confidence; to discourage
Example
The constant rejection letters began to dishearten the young writer.
継続的な拒否の手紙が若い作家を落胆させ始めた。
C1 verb /dɪˈpriːʃieɪt/

depreciate

価値が下がる
Meaning
to reduce in value over time
Example
Cars tend to depreciate quickly in their first few years.
車は最初の数年間で急速に価値が下がる傾向があります。
C1 adjective /dɪˈfɪʃənt/

Deficient

不足している
Meaning
not having enough of a specified quality or ingredient; lacking or inadequate
Example
His diet was deficient in essential vitamins.
彼の食事は必要なビタミンが不足していた。
C1 noun /ˈdaɪnəˌmoʊ/

dynamo

電気を発生させる機械; 大きなエネルギーと熱意を持つ人物
Meaning
A machine that generates electricity; a person with great energy and enthusiasm.
Example
She is the real dynamo behind the success of the company.
彼女は会社の成功の背後にある本物のダイナモです。
C1 noun dɪˌlɪb.əˈreɪ.ʃən

deliberation

熟考
Meaning
Long and careful consideration or discussion.
Example
The agreement was finalized after much deliberation.
その合意は多くの熟考の末に最終決定されました。
C1 noun /ˈdɛməɡɒɡ/

demagogue

デマゴーグ
Meaning
A political leader who seeks support by appealing to popular desires and prejudices rather than by using rational argument.
Example
The crowd was swayed by the fiery speeches of the demagogue.
群衆はデマゴーグの情熱的な演説に影響された。
C1 noun /djuːn/

dune

砂丘
Meaning
A hill or ridge of sand formed by the wind, usually found in deserts or near beaches.
Example
The children played on the sand dune by the beach.
子供たちはビーチの砂丘で遊んでいました。
C1 verb /dɪˈsɛnt/

dissent

Meaning
To hold or express opinions that are different from those officially accepted.
Example
Several members dissented from the majority decision.
C1 verb /dɪˈfeɪm/

defame

名誉毀損
Meaning
to harm someone's reputation by spreading false information
Example
He was defamed by malicious rumors.
彼は悪意のある噂で中傷されました。
C1 verb /ˌdɪsɪnˈtæŋɡl/

disentangle

ほどく
Meaning
To free something or someone from a tangle or complication.
Example
She tried to disentangle her hair from the branches.
彼女は枝から髪の毛をほどこうとしました。
C1 noun /ˈdɛspətɪzəm/

despotism

専制政治
Meaning
absolute power exercised in a cruel and oppressive way
Example
The people revolted against the era of despotism.
人々は専制政治の時代に反乱を起こしました。
C1 noun /ˈdiːvə/

diva

有名な女性歌手
Meaning
a famous female singer; a woman who is admired or behaves like a star
Example
The pop diva performed her latest hit to a cheering crowd.
ポップディーバは観衆の前で最新のヒットを披露しました。
C1 adjective /ˈdwɪndlɪŋ/

dwindling

減少
Meaning
Gradually reducing in number, size, or strength.
Example
The villagers relied on dwindling water supplies.
村人たちは減少していく水の供給に依存していた。
C1 adjective /ˌdaɪəˈbɒlɪkəl/

diabolical

悪魔的
Meaning
Wicked, cruel, or outrageously bad; resembling the devil.
Example
The dictator’s diabolical rule brought misery to the nation.
独裁者の悪魔的な支配は国に苦しみをもたらした。
C1 noun /ˈdɪs.ə.nəns/

dissonance

不協和音
Meaning
Disagreement, lack of harmony, conflict between ideas or beliefs.
Example
The cultural dissonance created misunderstandings.
文化的な不協和音が誤解を生んだ。
C1 verb /diːm/

deem

みなす, 判断する
Meaning
to regard or consider in a specified way
Example
The project was deemed a success by the board.
そのプロジェクトは理事会によって成功だと見なされました。
C1 adjective /dɪˈspɜːrst/

dispersed

散らばった
Meaning
Scattered or spread across a wide area.
Example
The dispersed population made it difficult to provide public services.
散らばった人口は公共サービスの提供を困難にしました。
C1 noun /deɪˈbɑː.kəl/

debacle

失敗
Meaning
A sudden and ignominious failure; a fiasco.
Example
The company's poor management led to a financial debacle.
会社の不十分な管理が財務的な失敗を招いた。
C1 adjective /drəˈkoʊniən/

draconian

ドラコニアン
Meaning
Extremely harsh and severe, especially laws or rules.
Example
The new regulations were criticized as draconian.
新しい規制はドラコニアンだと批判されました。
C1 adjective /dɪˈɡreɪdɪd/

degraded

劣化した
Meaning
Reduced in quality, dignity, or condition.
Example
The villagers were forced to live in degraded conditions.
村人たちは劣化した状態で暮らさざるを得なかった。
C1 verb /dɪsˈmæntəl/

dismantle

解体する
Meaning
to take apart; to remove or destroy the parts of
Example
Workers will dismantle the old bridge next month.
作業員たちは来月古い橋を解体します。
C1 verb /dɪsˈtrʌst/

distrust

不信
Meaning
to have no confidence or trust in someone or something
Example
Many people distrust politicians.
多くの人々は政治家を信用しません。
C1 adjective /dɪˈvaʊt/

devout

献身的
Meaning
Deeply religious or sincere.
Example
He is a devout believer who prays every day.
彼は毎日祈る献身的な信者です。
C1 verb /dɪˈmoʊt/

demote

降格
Meaning
to reduce to a lower rank or position
Example
The manager decided to demote the employee for poor performance.
マネージャーはパフォーマンスが悪いため、従業員を降格させることに決めました。
C1 noun /dɪˈfɔː.mə.ti/

Deformity

変形; 身体的欠陥
Meaning
a distorted or unnatural shape or form; physical malformation
Example
The accident caused a permanent deformity in his left hand.
事故は彼の左手に永続的な変形を引き起こしました。
C1 noun /ˈded.lɑk/

Dead-lock

行き詰まり; 停滞
Meaning
a situation in which no progress is possible; complete standstill
Example
The negotiations reached a deadlock when neither side would compromise.
交渉は行き詰まりに達し、どちらの側も妥協しようとしませんでした。
C1 noun /ˌdɪs.ɪˈluː.ʒən.mənt/

disillusionment

幻滅
Meaning
A feeling of disappointment resulting from the discovery that something is not as good as one believed it to be.
Example
Many people experience disillusionment after unrealistic expectations.
多くの人々が非現実的な期待の後に幻滅を経験します。
C1 adjective /ˈdɒdʒi/

Dodgy

疑わしい; 質が悪い; 信頼できない; 危険なまたはリスクのある
Meaning
suspicious; questionable; unreliable; risky or dangerous
Example
That deal sounds dodgy to me.
その取引は私には疑わしく聞こえます。
C1 adjective dɪˈskrɪmɪnətɔːri

discriminatory

差別的
Meaning
Making or showing an unfair or prejudicial distinction between different categories of people or things.
Example
Discriminatory policies triggered protests.
差別的な政策は抗議を引き起こしました。
C1 noun /dɜːrθ/

dearth

不足
Meaning
A scarcity or lack of something.
Example
There was a dearth of food during the famine.
飢饉の間に食料が不足していた。
C1 noun /dɪˈmiːnər/

demeanor

態度
Meaning
a person's outward behavior or appearance
Example
Her calm demeanor impressed everyone at the meeting.
彼女の冷静な態度は会議で皆に感銘を与えました。
C1 verb /ˈdɪs.ɪ.peɪt/

dissipate

徐々に消失する
Meaning
To disappear or cause to disappear gradually.
Example
The tension in the room slowly dissipated.
部屋の中の緊張感は徐々に消えていった。
C1 verb ˈdwɪn.dl

dwindle

減少する
Meaning
To diminish gradually in size, amount, or strength; to become progressively smaller.
Example
His savings dwindled due to unexpected expenses.
予期しない支出のため、彼の貯金は減少しました。
C1 adjective /dɪsˈhɑːrtənd/

Disheartened

落胆した
Meaning
discouraged; feeling dejected; losing hope or confidence
Example
She felt disheartened after failing the exam twice.
彼女は試験に2回失敗した後、落胆していました。
C1 verb /dɪˈbɑːr/

debar

禁止する
Meaning
To officially prevent someone from doing something.
Example
He was debarred from entering the competition due to cheating.
彼は不正行為のため競技への参加が禁止されました。
C1 noun /ˌdɜːrməˈtɑːlədʒɪst/

dermatologist

皮膚科医
Meaning
A doctor who specializes in the treatment of skin diseases.
Example
She consulted a dermatologist for her skin allergy.
彼女は皮膚のアレルギーのために皮膚科医に相談した。
C1 noun ˈdaɪ.nə.sti

dynasty

王朝
Meaning
A line of hereditary rulers of a country; a succession of people from the same family who play a prominent role in business, politics, or another field.
Example
The Ming dynasty ruled China for centuries.
明王朝は何世紀にもわたって中国を支配していました。
C1 noun /dɪˌlɪb.əˈreɪ.ʃənz/

deliberations

審議
Meaning
Careful consideration and discussion before making decisions.
Example
Deliberations on sustainability continued for hours.
持続可能性についての審議は何時間も続きました。
C1 adjective /ˈdeɪnti/

dainty

優雅で可愛らしい
Meaning
Delicately small, pretty, and often considered elegant.
Example
She wore a dainty necklace made of pearls.
彼女は真珠でできた繊細なネックレスをしていました。
C1 verb /diːˈfɒrɪst/

deforest

Meaning
to clear an area of trees, usually on a large scale
Example
The region has been heavily deforested for agriculture.
C1 noun /dɪˈsaɪ.pəl/

Disciple

弟子; 信者
Meaning
a follower and student of a teacher, leader, or philosopher; devoted follower
Example
The famous philosopher had many disciples who spread his teachings worldwide.
その有名な哲学者には多くの弟子がいて、彼の教えを世界中に広めました。
C1 noun dɪˈfleɪʃən

deflation

デフレーション
Meaning
Reduction of the general level of prices in an economy.
Example
Deflation often leads to decreased consumer spending.
デフレーションはしばしば消費者の支出を減少させる。
C1 noun /ˈdæmpər/

damper

力、効果、または興奮を減少または抑制するもの
Meaning
something that reduces or lessens the force, effect, or excitement
Example
The cancellation of the trip put a damper on their enthusiasm.
旅行のキャンセルは彼らの熱意をそぐことになった。
C1 verb /dɪˈstɪl/

distill

Meaning
To purify a liquid by heating and cooling; to extract the essential meaning or most important aspects.
Example
The factory distills water to make it safe for drinking.
C1 noun /ˈdæn.drʌf/

Dandruff

フケ
Meaning
small white or grey flakes of dead skin that form on the scalp and fall from the hair
Example
He used a special shampoo to treat his persistent dandruff problem.
彼は慢性的なフケの問題を治すために、特別なシャンプーを使った。
C1 adjective daɪˈvɜː.dʒənt

divergent

異なる
Meaning
Tending to be different or develop in different directions
Example
Divergent policies create challenges in collaboration.
異なる政策は協力に挑戦を生み出します。
C1 noun ˈdɪk.ʃən

diction

発音と単語の選択
Meaning
The style of pronunciation and word choice in speaking or writing.
Example
A strong diction enhances communication skills.
強いディクションはコミュニケーション能力を向上させます。
C1 adjective /daɪˈvɜːrsɪfaɪd/

diversified

多様化された
Meaning
Made or having variety in form, nature, or content.
Example
The company adopted a diversified business strategy to reduce risks.
その会社はリスクを減らすために多様化されたビジネス戦略を採用した。
C1 adjective /dɪˈstrɔːt/

distraught

動揺した
Meaning
extremely upset and anxious, often to the point of being unable to think clearly
Example
She was distraught after losing her pet.
ペットを失った後、彼女は動揺していた。
C1 adjective /ˌdɪfəˈrɛnʃəl/

differential

差別的
Meaning
Relating to or showing a difference; involving a distinction.
Example
There is a differential treatment between the two groups.
2つのグループ間に差別的な扱いがあります。
C1 noun dɪˈdʒɛnəˌreɪtɪv dɪˈzizɪz

degenerative diseases

変性疾患
Meaning
Medical conditions that involve the deterioration or progressive decline of tissues, organs, or functions
Example
Degenerative diseases are common in an aging population.
変性疾患は高齢化した人口に一般的です。
C1 noun ˌdɪdʒɪˈnɛəreɪʃən

degeneration

退化
Meaning
The process of decline or deterioration in structure or function.
Example
The degeneration of brain cells leads to cognitive decline.
脳細胞の退化は認知機能の低下を引き起こします。
C1 noun /dɪˈprɛsənt/

depressant

抑制剤
Meaning
A drug that reduces functional or nervous activity in the body.
Example
Alcohol acts as a depressant on the central nervous system.
アルコールは中枢神経系に抑制剤として作用します。
C1 verb /daɪˈvɜːrdʒ/

diverge

分岐する
Meaning
to separate and go in different directions; to differ
Example
The two paths diverge at the fork in the road.
二つの道は交差点で分かれる。
C1 adjective /dɪˈrɒɡətɔːri/

derogatory

侮辱的
Meaning
Showing a critical or disrespectful attitude.
Example
The article contained derogatory comments about the politician.
その記事には政治家について侮辱的なコメントが含まれていました。
C1 adjective /ˈdɑːsəl/ or /ˈdəʊsaɪl/

docile

従順な
Meaning
easily managed, taught, or controlled; submissive
Example
The docile puppy quickly learned new tricks.
従順な子犬はすぐに新しい技を覚えました。
C1 noun/adjective /dɪˈtɜː.rənt/

deterrent

抑止力
Meaning
A thing that discourages or is intended to discourage someone from doing something.
Example
A strict law serves as a deterrent to crime.
厳格な法律は犯罪の抑止力として機能します。
C1 verb /daʊs/

douse

消す / 注ぐ
Meaning
to pour liquid over; to extinguish a fire or light
Example
Firefighters doused the flames with water.
消防士たちは水で炎を消しました。
C1 adjective /dɪˈfaɪənt/

Defiant

反抗的な; 逆らう
Meaning
boldly resistant or challenging; disobedient
Example
The defiant student refused to follow the rules.
その反抗的な学生はルールに従うことを拒否しました。
C1 verb /dɪˈtɛst/

detest

嫌う
Meaning
To dislike intensely or hate.
Example
I detest waking up early on weekends.
私は週末に早起きするのが嫌いです。
C1 noun /dɪˈskrep.ən.si/

discrepancy

不一致, 差異, 矛盾
Meaning
A lack of compatibility or similarity between two or more facts.
Example
The audit revealed a discrepancy between the reported earnings and actual income.
監査は報告された収入と実際の収入との間に不一致があることを明らかにしました。
C1 verb /dɪˈluːd/

delude

だます
Meaning
To mislead someone into believing something that is not true.
Example
He deluded himself into thinking he could win the race without training.
彼は訓練なしでレースに勝てると思い込み、自分をだました。
C1 noun /ˈdaʊri/

dowry

持参金
Meaning
Property or money brought by a bride to her husband at marriage.
Example
The dowry tradition is still followed in some cultures.
いくつかの文化では、持参金の伝統が今でも守られています。
C1 noun /ˌdɪsərˈteɪʃən/

dissertation

論文
Meaning
A long piece of writing on a particular subject, usually written for a university degree.
Example
She spent two years writing her doctoral dissertation.
彼女は博士論文を書くのに2年を費やしました。
C1 noun /ˈdɔːrˌkiːpər/

doorkeeper

門番
Meaning
A person whose job is to guard or manage the entrance of a building or room.
Example
The doorkeeper checked everyone’s passes before they entered the hall.
ドアキーパーは皆がホールに入る前に通行証を確認した。
C1 adjective /dɪˈbeɪst/

debased

劣化した
Meaning
having lost quality, value, or moral character
Example
The debased currency lost the trust of the people.
劣化した通貨は人々の信頼を失った。
C1 verb /daɪˈluːt/

dilute

薄める
Meaning
To make a liquid thinner or weaker by adding water or another solvent.
Example
You should dilute the juice with water before serving it to children.
子供たちに出す前にジュースを水で薄めるべきです。
C1 adjective /ˈdaʊn.kæst/

downcast

Meaning
feeling sad, dejected, or with lowered eyes
Example
He looked downcast after hearing the bad news.
C1 noun /dɪˈluːʒən/

delusion

錯覚
Meaning
A false belief or impression maintained despite being contradicted by reality.
Example
He lived under the delusion that he was invincible.
彼は自分が無敵だという錯覚の中で生きていた。
C1 noun /dɪˈten.ʃən/

Detention

停学; 拘留
Meaning
the action of detaining someone or being detained in official custody
Example
The student received detention for repeatedly disrupting the class.
生徒は繰り返しクラスを乱したため、停学を受けました。
C1 noun /ˈdɛmənˌstreɪtər/

demonstrator

デモンストレーター, 抗議者
Meaning
a person who shows how something works or takes part in a public protest
Example
The demonstrators marched peacefully through the city streets.
デモ参加者は平和的に街の通りを行進しました。
C1 verb /dɪˈvɒlv/

devolve

委譲する
Meaning
To pass power, responsibility, or duties to another person or group.
Example
The responsibility will devolve on the new manager.
責任は新しいマネージャーに委譲されます。
C1 noun ˈdɛf.ər.əns

deference

敬意
Meaning
Humble submission and respect.
Example
He showed deference to his elderly mentor.
彼は年上のメンターに敬意を示しました。
C1 adjective /dɪˈvɪzəbl/

divisible

割り切れる
Meaning
Capable of being divided by another number without leaving a remainder.
Example
Twelve is divisible by three and four.
12は3と4で割り切れます。
C1 noun /ˌdɛrɪˈveɪʃən/

derivation

派生
Meaning
The origin or development of something from a source.
Example
The derivation of the word comes from Latin.
その単語の起源はラテン語から来ている。
C1 verb /dɪsˈoʊn/

disown

拒絶する
Meaning
to refuse to acknowledge or accept responsibility for someone or something
Example
He decided to disown his reckless brother.
彼は無謀な兄を拒絶する決断をしました。
C1 verb/adjective /dɪˈdʒɛnəreɪt/

degenerate

堕落する
Meaning
To decline or deteriorate in quality, character, or condition; or someone with low moral standards.
Example
The once thriving empire began to degenerate into chaos.
かつて繁栄していた帝国は混沌に堕ち始めました。
C1 adjective /ˈdaʊ.ər/

dour

厳格
Meaning
relentlessly severe, stern, or gloomy in manner or appearance
Example
His dour expression made the meeting uncomfortable.
彼の厳格な表情は会議を不快にした。
C1 noun /ˌdaɪəˈrɑːmə/

diorama

ジオラマ
Meaning
a three-dimensional model representing a scene, often with miniature figures
Example
The museum displayed a diorama of an ancient village.
博物館に古代の村のジオラマが展示されていました。
C1 noun /ˌdɪp.ləˈmæt.ɪk ˈmaɪl.stəʊn/

diplomatic milestone

外交上のマイルストーン
Meaning
A significant achievement or important event in diplomatic relations.
Example
Hosting the summit was a diplomatic milestone.
サミットの開催は外交上のマイルストーンでした。
C1 adjective dɪ ˈskrɛʃ.ən.er.i

discretionary

裁量の
Meaning
Available for use at the discretion of the user; not required or mandatory.
Example
He set aside some discretionary income for travel.
彼は旅行のためにいくらかの裁量所得を取っておいた。
C1 noun /ˈdɪɡnɪˌtɛri/

dignitary

重要人物
Meaning
a person considered to be important because of high rank or office
Example
Several foreign dignitaries attended the state banquet.
数人の外国の重要人物が国の晩餐会に出席しました。
C1 noun dɪˈpliː.ʃən

depletion

枯渇
Meaning
The gradual reduction or exhaustion of a resource or substance.
Example
Overuse of groundwater leads to depletion of water resources.
地下水の過剰使用は水資源の枯渇を引き起こす。