intrepid
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C1 adjective /ɪnˈtrɛpɪd/

intrepid

勇敢な
Meaning
fearless and adventurous, often used humorously
Example
The intrepid traveler explored the jungle alone.
その勇敢な旅行者は一人でジャングルを探検した。
C1 adjective /ɪmˈpɜːrviəs/

impervious

透過しない
Meaning
Not allowing fluid to pass through; unable to be affected by something.
Example
The jacket is impervious to rain.
ジャケットは雨に透過しません。
C1 adjective /ɪnˈfleɪtɪd/

inflated

膨らんだ
Meaning
excessively increased in size, value, or importance; filled with air or gas
Example
The company faced criticism for its inflated prices.
その会社は膨らんだ価格で批判を受けました。
C1 noun /ɪnˈfjuːʒən/

infusion

注入
Meaning
the act of introducing something into another; a drink made by steeping leaves or herbs in liquid
Example
She prepared a calming infusion of chamomile tea.
彼女はカモミールティーの落ち着く注入を準備しました。
C1 noun /ˌɪnfɪˈdɛləti/

infidelity

不倫
Meaning
the act of being unfaithful to a spouse or partner
Example
Their marriage ended due to his infidelity.
彼らの結婚は彼の不倫が原因で終わった。
C1 adjective /ˌɪmprɪˈsaɪs/

imprecise

不正確
Meaning
Not exact or accurate; vague.
Example
His explanation was too imprecise to be helpful.
彼の説明はあまりにも不正確で役に立たなかった。
C1 adjective /ˌɪndɪˈskraɪbəbəl/

Indescribable

言葉では表現できない
Meaning
impossible to describe or express in words; beyond description
Example
The beauty of the sunset was indescribable.
夕日の美しさは言葉では表現できないほどでした。
C1 adjective /ˈɪntrɪkət/

intricate

複雑
Meaning
very detailed, complex, and difficult to understand
Example
The artist created an intricate pattern on the wall.
アーティストは壁に複雑な模様を作り出しました。
C1 adjective /ɪˈrɛpərəbəl/

Irreparable

修復不可能
Meaning
impossible to repair or fix; permanent damage that cannot be undone
Example
The accident caused irreparable damage to his spine.
その事故は彼の背骨に修復不可能な損傷を与えました。
C1 adjective ɪnˈkʌm.bənt

incumbent

義務的な
Meaning
necessary for (someone) as a duty or responsibility.
Example
It is incumbent upon all citizens to obey the law.
すべての市民が法律を守るのは義務である。
C1 verb /ˈɪrɪˌɡeɪt/

irrigate

灌漑する
Meaning
to supply water to land or crops; to wash out a wound with water
Example
Farmers irrigate their fields during dry seasons.
農家は乾季に畑に灌漑を行います。
C1 noun /ˌɪntərˈmɪʃən/

intermission

休憩
Meaning
A pause or break, especially during a performance or event.
Example
The play had a twenty-minute intermission.
その劇には20分間の休憩がありました。
C1 noun /ˈɪmɪdʒəri/

imagery

イメージ
Meaning
visually descriptive or figurative language, especially in a literary work
Example
The poet's use of imagery brought the scene to life.
詩人のイメージの使用は、シーンに命を吹き込みました。
C1 noun /ˌɪnækˈtɪvɪti/

inactivity

不活動
Meaning
the state of not being active physically or mentally; lack of action
Example
Prolonged inactivity can negatively affect both physical and mental health.
長期間の不活動は身体的および精神的健康に悪影響を与えます。
C1 noun /ɪˈmiːdiəsi/

immediacy

即時性, 緊迫感
Meaning
The quality of bringing one into direct and instant involvement with something, giving rise to a sense of urgency or excitement.
Example
The immediacy of digital communication has reshaped business operations.
デジタルコミュニケーションの即時性は、ビジネスの運営方法を変えました。
C1 noun ˌɪn.toʊˈneɪ.ʃən

intonation

イントネーション
Meaning
The rise and fall of tone in speech and pronunciation.
Example
Proper intonation enhances the clarity of a speech.
適切なイントネーションはスピーチの明確さを高めます。
C1 adjective /aɪˈreɪt/

irate

激怒した
Meaning
Extremely angry.
Example
The customer became irate after waiting for hours.
顧客は何時間も待った後、激怒しました。
C1 noun /ɪnˈdɪf.ər.əns/

Indifference

無関心; 無関心さ; アパシー
Meaning
lack of interest, concern, or sympathy; the state of not caring about something
Example
His indifference to his studies resulted in poor grades throughout the semester.
彼の学業に対する無関心さが、学期中ずっと悪い成績をもたらした。
C1 verb /ɪmˈpɑːrt/

impart

伝える
Meaning
to make information known; to bestow or communicate
Example
The teacher imparted valuable knowledge to her students.
教師は生徒に貴重な知識を授けました。
C1 adjective /ˌɪnkəʊˈhɪərənt/

incoherent

一貫性のない
Meaning
Not clear or easy to understand; lacking logical connection.
Example
His explanation was so incoherent that nobody could follow it.
彼の説明はあまりにも一貫性がなく、誰もそれを追うことができませんでした。
C1 adjective /ˌɪnkənˈsiːvəbl̩/

inconceivable

想像できない
Meaning
Impossible to imagine or believe; beyond comprehension.
Example
It seemed inconceivable that she could finish the marathon after such little training.
彼女があれほどのトレーニングでマラソンを完走できるとは想像できなかった。
C1 verb /ɪnˈdaɪt/

indict

起訴する
Meaning
to formally accuse someone of committing a serious crime
Example
The grand jury decided to indict the politician for corruption.
大陪審団は腐敗のために政治家を起訴することを決定した。
C1 noun ˌɪn.fɪlˈtreɪ.ʃən

infiltration

浸透、秘密のアクセス
Meaning
The process of entering or gaining access to an organization or place surreptitiously.
Example
Cybersecurity prevents infiltration into sensitive data.
サイバーセキュリティは、機密データへの浸透を防ぎます。
C1 verb /ˌɪntəˈsɛkt/

intersect

交差する
Meaning
to cross or pass through each other
Example
The two roads intersect at the city center.
二つの道路は市内中心で交差する。
C1 adjective /ˌɪnstənˈteɪniəs/

instantaneous

即時
Meaning
Happening immediately, without any delay.
Example
The change in temperature was almost instantaneous.
温度の変化はほぼ即時でした。
C1 adjective /ˈɪmpjəd(ə)nt/

impudent

無礼な、厚かましい
Meaning
not showing due respect for another person; rude
Example
The impudent child talked back to the teacher.
その無礼な子供は先生に逆らった。
C1 noun /ɪnˈtɛstɪn/

intestine

腸
Meaning
The part of the digestive system where food is digested and absorbed, extending from the stomach to the anus.
Example
The doctor explained how nutrients are absorbed in the small intestine.
医者は、小腸で栄養素がどのように吸収されるかを説明しました。
C1 adjective /ɪnˈɛlɪdʒəbəl/

Ineligible

不適格; 無資格; 選ばれない
Meaning
not qualified or entitled to participate or be chosen; unsuitable
Example
Students with poor grades are ineligible for the scholarship program.
成績が悪い学生は奨学金プログラムに応募できません。
C1 adjective /ɪˈrɛvərənt/

irreverent

不敬な
Meaning
showing a lack of respect for people or things that are usually respected
Example
The comedian’s irreverent jokes offended some of the audience.
コメディアンの不敬なジョークは、観客の一部を不快にさせた。
C1 adverb /ˌɪn.ədˈvɜːr.tənt.li/

Inadvertently

うっかり; ついうっかり; 誤って
Meaning
without being aware of what you are doing; unintentionally; by mistake
Example
She inadvertently deleted the important file while cleaning her computer.
彼女はコンピュータを掃除しているとき、重要なファイルをうっかり削除してしまった。
C1 verb /ɪnˈfrɪndʒ/

infringe

侵害する
Meaning
To actively break the terms of a law, agreement, or right.
Example
Copying this software without permission will infringe copyright laws.
許可なくこのソフトウェアをコピーすると著作権法を侵害することになります。
C1 adjective /ˌɪnækˈsɛsəbl/

inaccessible

アクセスできない
Meaning
unable to be reached, entered, or understood
Example
The remote village is almost inaccessible during the rainy season.
その遠隔地の村は雨季にはほとんどアクセスできません。
C1 adjective /ɪnˈæk.tɪv/

Inactive

非アクティブ
Meaning
not active; not working; dormant; idle
Example
The volcano has been inactive for over a century.
この火山は1世紀以上も活動していない。
C1 noun /ˈɪnsɪdəns/

incidence

発生率
Meaning
the occurrence, rate, or frequency of something
Example
The incidence of road accidents has decreased this year.
今年の道路事故の発生率は減少しました。
C1 noun /ɪmˈpɛd.ɪ.mənt/

impediment

障害
Meaning
A hindrance or obstruction in doing something; something that prevents progress.
Example
Lack of funds is a major impediment to the project.
資金不足はプロジェクトの大きな障害です。
C1 verb /ɪnˈkɑːrsəreɪt/

incarcerate

投獄する
Meaning
to imprison or confine someone
Example
The authorities incarcerated the criminal after the trial.
当局は裁判後に犯罪者を投獄しました。
C1 verb /ɪˈnɔːɡjʊreɪt/

inaugurate

Meaning
To formally begin or introduce something, especially with a ceremony.
Example
The mayor will inaugurate the new bridge tomorrow.
C1 verb /ˈɪnsjuleɪt/

insulate

Meaning
To protect something by covering it, especially to prevent heat, sound, or electricity from escaping or entering.
Example
The house was insulated to reduce heating costs.
C1 adjective ˈɪn.tər.ɪm

interim

暫定的
Meaning
In or for the intervening period; provisional or temporary.
Example
Interim governments manage transitional phases.
暫定政府は移行段階を管理します。
C1 noun /ˈɪnkwest/

inquest

調査
Meaning
A legal or official inquiry, especially into the cause of a death.
Example
The inquest revealed the cause of the accident.
調査は事故の原因を明らかにしました。
C1 noun ˌɪntədɪˈpɛndənsi

interdependency

相互依存
Meaning
The dependence of two or more people or things on each other.
Example
The interdependency of the countries led to greater cooperation.
国々の相互依存は、より大きな協力を生み出しました。
C1 adjective ˌɪn.tə.dʒen.əˈreɪ.ʃən.əl

intergenerational

世代間、異なる世代間で発生する
Meaning
Existing or occurring between different generations of a family.
Example
Intergenerational wisdom ensures cultural continuity.
インタージェネレーショナルな知恵は文化的継続性を確保する。
C1 noun ˌɪnˈsaɪtfʊlnɪs

insightfulness

洞察力、分析能力
Meaning
The capacity to gain an accurate and deep intuitive understanding of a person or thing.
Example
His insightfulness helped solve the complex problem.
彼の洞察力は複雑な問題を解決するのに役立ちました。
C1 adjective /ɪmˈprɒmp.tjuː/

impromptu

即興
Meaning
Done without being planned, organized, or rehearsed; spontaneous.
Example
He gave an impromptu speech at the event.
彼はイベントで即興のスピーチを行いました。
C1 adjective /ˌɪrɪˈvɜːrsəbl/

irreversible

不可逆な
Meaning
Not able to be undone, changed, or reversed.
Example
The damage caused by the fire was irreversible.
火事によって生じた損害は不可逆でした。
C1 noun /ɪmˌpɜː.sənˈeɪ.ʃən/

impersonation

なりすまし
Meaning
The action of pretending to be another person for the purpose of entertainment or fraud.
Example
Online impersonation is a serious cybercrime.
オンラインでのなりすましは重大なサイバー犯罪です。
C1 adjective /ˌɪnəˈtɛntɪv/

inattentive

不注意な
Meaning
not paying attention; lacking focus or concentration
Example
The inattentive student missed several important instructions.
不注意な学生は重要な指示をいくつも逃した。
C1 noun /ˈɪn.tə.lekt/

intellect

知能
Meaning
The ability to think, reason, and understand objectively.
Example
Her intellect is admired by all her colleagues.
彼女の知能はすべての同僚に賞賛されています。
C1 noun ˈɪn.fər.əns

inference

推論
Meaning
A conclusion reached on the basis of evidence and reasoning; logical deduction.
Example
Scientists make inferences based on experimental data.
科学者たちは実験データに基づいて推論を行います。
C1 noun /ɪnˈkɒmpɪtəns/

incompetence

無能
Meaning
Lack of ability, skill, or effectiveness in doing something.
Example
The project failed due to the manager’s incompetence.
プロジェクトはマネージャーの無能のため失敗しました。
C1 adjective /ɪmˈpɑːrʃəl/

Impartial

公正; 中立的
Meaning
treating all sides fairly; unbiased; neutral
Example
A good judge must remain impartial throughout the trial.
優れた裁判官は裁判中に公正を保たなければなりません。
C1 noun /ˌɪn.səˌbɔːr.dɪˈneɪ.ʃən/

insubordination

反抗
Meaning
Defiance of authority; refusal to obey orders.
Example
The soldier was punished for insubordination during the mission.
その兵士はミッション中の反抗で罰せられました。
C1 verb ɪmˈbjuː

Imbue

誰かの心にアイデアや感情を深く浸透させる
Meaning
Mixing some idea or feeling deeply into someone's mind
Example
The teacher tried to imbue students with a love for learning.
教師は学生に学びへの愛を伝えようとした。
C1 adjective /ɪmˈpɜːrtɪnənt/

impertinent

無礼な
Meaning
rude and showing a lack of respect
Example
It was impertinent of him to question the manager's decision.
マネージャーの決定に疑問を呈するのは無礼でした。
C1 adjective /ˌɪn.ɪˈfɛk.tʃu.əl/

ineffectual

効果がない
Meaning
Not producing any or the desired effect; lacking the ability or qualities to achieve a purpose.
Example
The manager’s ineffectual leadership caused the team to lose motivation.
マネージャーの効果がないリーダーシップは、チームがモチベーションを失う原因となった。
C1 verb /ɪnˈvɜːrt/

invert

逆さにする
Meaning
To turn something upside down or in the opposite position, order, or direction.
Example
He inverted the glass to let the water drain out.
彼は水が流れ出るようにグラスを逆さまにしました。
C1 noun /aɪl/

isle

小さな島
Meaning
A small island or peninsula, often poetic or literary.
Example
They spent their honeymoon on a beautiful tropical isle.
彼らは美しい熱帯の島でハネムーンを過ごしました。
C1 adjective /ˈɪrɪtəbl/

irritable

Meaning
easily annoyed or made angry
Example
She became irritable after working long hours without rest.
C1 adjective /ˌaɪdiəˈlɪstɪk/

Idealistic

理想主義的
Meaning
pursuing high principles or ideals; unrealistically optimistic
Example
She has an idealistic view of changing the world.
彼女は世界を変えるという理想主義的な見方を持っています。
C1 verb /ɪmˈpɒvərɪʃ/

impoverish

貧困にする
Meaning
To make someone poor or reduce the quality or richness of something.
Example
The long war impoverished the entire nation.
長い戦争が国全体を貧困にした。
C1 noun /ɪnˈdɪɡ.nə.ti/

Indignity

屈辱
Meaning
treatment or circumstances that cause one to feel shame or loss of dignity; humiliation
Example
She refused to suffer the indignity of being searched without proper cause.
彼女は正当な理由もなく荷物検査を受けるという屈辱に耐えることを拒んだ。
C1 verb /ɪnˈvælɪdeɪt/

invalidate

無効にする
Meaning
To make something not valid or legally acceptable.
Example
The new evidence may invalidate the previous ruling.
新しい証拠が前の判決を無効にするかもしれません。
C1 adjective /ɪnˈhɪbɪtɪd/

inhibited

抑制された
Meaning
Unable to act in a relaxed and natural way, especially due to self-consciousness or restraint.
Example
He was too inhibited to express his true feelings.
彼は自分の本当の感情を表現するにはあまりにも抑制されていた。
C1 adjective /ɪnˈdetɪd/

Indebted

借金がある; 感謝している
Meaning
owing money or gratitude to someone; obligated; grateful
Example
I am deeply indebted to my teacher for all her guidance.
私は先生のすべての指導に深く感謝しています。
C1 noun /ɪnˈsɜːʃən/

insertion

挿入
Meaning
the action of inserting something into something else
Example
The insertion of the new data was completed successfully.
新しいデータの挿入は成功裏に完了しました。
C1 noun /ˌɪnkwɪˈzɪʃən/

inquisition

尋問
Meaning
A prolonged and intense questioning or investigation, often harsh in nature.
Example
The journalist faced an inquisition from the panel about his sources.
ジャーナリストは、自分の情報源に関するパネルからの厳しい尋問に直面した。
C1 noun /ˌɪntərˈdʒɛkʃən/

interjection

感嘆詞
Meaning
a word or phrase used to express sudden emotion or reaction, often standing alone
Example
Words like 'wow' and 'ouch' are common interjections in English.
'わお'や'痛っ'は英語でよく使われる感嘆詞です。
C1 adjective /ɪnˈdʌldʒənt/

indulgent

寛容な
Meaning
Having a tendency to be overly generous or lenient with someone.
Example
The indulgent mother allowed her child to stay up late.
寛容な母は子供を遅くまで起きていることを許しました。
C1 adjective /ɪnˈsɛp(ə)rəbəl/

inseparable

切り離せない
Meaning
Unable to be separated or always together.
Example
The two friends have been inseparable since childhood.
二人の友達は子供の頃から切り離せないです。
C1 adjective /ɪnˈhjuːmən/

Inhuman

非人道的
Meaning
lacking human qualities of compassion and mercy; cruel or barbaric
Example
The prisoners were kept in inhuman conditions.
囚人たちは非人道的な状況で収容されていました。
C1 noun /ˈɪnkjʊˌbeɪtər/

incubator

インキュベーター
Meaning
a device or environment that provides suitable conditions for eggs, cells, or infants to develop
Example
The premature baby was placed in an incubator for care.
未熟児はケアのためにインキュベーターに入れられました。
C1 adjective /ɪnˈdʌktɪv/

inductive

帰納的
Meaning
characterized by the inference of general laws from particular instances; reasoning from specific cases to general principles
Example
The scientist used inductive reasoning to form a hypothesis.
科学者は帰納的推論を使って仮説を立てました。
C1 verb /ɪnˈkrɪmɪˌneɪt/

incriminate

有罪にする
Meaning
to make someone appear guilty of a crime or wrongdoing
Example
The new evidence could incriminate the suspect in the robbery case.
新しい証拠がロビー事件の容疑者を有罪にする可能性があります。
C1 noun /ˌaɪ.diˈɒl.ə.dʒi/

ideology

イデオロギー
Meaning
A system of ideas and ideals, especially one that forms the basis of economic or political theory and policy.
Example
Democracy is based on the ideology of freedom and equality.
民主主義は自由と平等のイデオロギーに基づいています。
C1 adjective /ˌaɪ.di.əˈlɒdʒ.ɪ.kəl/

ideological

イデオロギー的
Meaning
Relating to or based on a system of ideas or beliefs.
Example
The two parties are divided by deep ideological differences.
二つの党は深いイデオロギー的な違いによって分裂している。
C1 adjective /ɪˈmjuː.tə.bəl/

immutable

不変の
Meaning
Unchangeable, permanent, or fixed
Example
The laws of physics are considered immutable.
物理法則は不変と見なされます。
C1 adjective ɪˈluː.sər.i

illusory

幻の
Meaning
Based on illusion; not real although seeming to be.
Example
His sense of security was entirely illusory.
彼の安全感は完全に幻のものだった。
C1 verb /ɪnˈskraɪb/

inscribe

刻む
Meaning
to write or carve words or symbols on a surface
Example
They inscribed her name on the trophy.
彼らはトロフィーに彼女の名前を刻みました。
C1 noun /ɪˌreɡjəˈlærɪti/

irregularity

不規則性
Meaning
lack of regularity or consistency; a deviation from what is normal, expected, or orderly
Example
The audit revealed several financial irregularities in the company’s records.
監査により、その会社の記録にいくつかの財務上の不規則性が明らかになった。
C1 noun /ˌɪmpɔːrˈteɪʃən/

importation

輸入
Meaning
The act of bringing goods or services into a country from abroad
Example
The importation of luxury goods is strictly regulated.
高級品の輸入は厳しく規制されています。
C1 verb /ˈɪnfɪltreɪt/

infiltrate

浸透
Meaning
to secretly enter or gain access to a place or group
Example
The spies managed to infiltrate the enemy base.
スパイたちは敵基地に infiltrate できた。
C1 adjective /ɪmˈpʌlsɪv/

impulsive

衝動的な, 直感的な
Meaning
acting suddenly without careful thought
Example
She made an impulsive decision to buy the car.
彼女は衝動的な決定で車を買うことにしました。
C1 verb /ɪnˈsaɪt/

incite

扇動する
Meaning
to provoke; to stir up
Example
His speech incited the crowd to violence.
彼のスピーチは群衆を暴力に駆り立てた。
C1 verb /ɪmˈplɔːr/

implore

Meaning
To beg someone earnestly or desperately to do something.
Example
She implored him to stay with her.
C1 adjective /ˌɪnkɒmprɪˈhɛnsəbl/

incomprehensible

理解不能
Meaning
Impossible or very difficult to understand.
Example
The professor’s lecture was so fast it became incomprehensible.
教授の講義は速すぎて理解不能になった。
C1 adjective /ˌɪnədˈmɪsəbl̩/

inadmissible

受け入れられない
Meaning
Not allowed, especially as evidence in a court of law.
Example
The judge ruled the evidence inadmissible.
裁判官は証拠を受け入れられないと判断しました。
C1 adjective /ˌɪntərˈtʃeɪndʒəbl/

interchangeable

交換可能な
Meaning
able to be exchanged with each other without difference or loss of function
Example
These machine parts are interchangeable, so they can be replaced easily.
これらの機械部品は交換可能なため、簡単に交換できます。
C1 adjective /ɪnˈdiːsənt/

indecent

不品な
Meaning
not conforming to accepted standards of behavior or morality; improper or offensive
Example
He was warned for making an indecent remark during the meeting.
彼は不品な発言で注意された。
C1 noun /ɪnˈdaɪtmənt/

indictment

起訴状
Meaning
a formal charge or accusation of a serious crime
Example
The indictment accused the company of multiple violations.
起訴状は、会社に対する複数の違反を告発しました。
C1 noun /ɪnˈhɛrɪtər/

inheritor

相続人
Meaning
a person who receives money, property, or a title when someone dies
Example
She became the inheritor of her family's estate.
彼女は家族の財産の相続人となった。
C1 verb /ɪmˈpiːtʃ/

impeach

Meaning
To charge a public official with misconduct while in office.
Example
The parliament voted to impeach the president.
C1 adjective /ɪˈlɒdʒ.ɪ.kəl/

Illogical

非論理的
Meaning
not reasonable or sensible; lacking logic
Example
It would be illogical to go swimming in such cold weather.
こんなに寒い天気で泳ぐのは非論理的です。
C1 adjective /ˌɪməˈtɪəriəl/

immaterial

無関係
Meaning
Not important or relevant; lacking physical substance.
Example
The judge ruled that the argument was immaterial to the case.
裁判官はその議論が事件に関係ないと判断しました。
C1 noun /ɪnˈsek.tɪ.saɪd/

Insecticide

殺虫剤
Meaning
a substance used for killing insects; a chemical pesticide that targets insects
Example
The farmer sprayed insecticide on his crops to protect them from harmful bugs.
農夫は作物を有害な虫から守るために殺虫剤を噴霧しました。
C1 adjective /ɪˈmeʒərəbəl/

Immeasurable

計り知れない
Meaning
too large or extensive to measure; boundless
Example
The immeasurable love of a mother knows no bounds.
母の計り知れない愛には限界がない。
C1 adjective /ˌɪntərˈtwaɪnd/

intertwined

幸福
Meaning
closely connected or twisted together
Example
Their lives became deeply intertwined after the accident.
彼女は賞を受け取ったとき、幸せを隠せませんでした。
C1 adjective /ɪnˈtɜːrmənəbl/

interminable

終わりのない
Meaning
Seemingly endless; having no apparent end.
Example
The meeting felt interminable and exhausting.
会議は終わりのない疲れるもののように感じた。
C1 noun /ɪnˈsæn.ə.ti/

Insanity

狂気; 精神疾患
Meaning
the state of being seriously mentally ill; extreme foolishness or irrationality
Example
The defense lawyer argued that his client was not guilty by reason of insanity.
弁護人は、被告人が狂気によって無罪であると主張した。
C1 adjective /ɪnˈflæməbəl/

Inflammable

可燃; 発火性
Meaning
easily set on fire; flammable; combustible
Example
The inflammable material caught fire quickly.
その可燃性材料はすぐに火をつけました。
C1 adjective /ɪnˈfriːkwənt/

infrequent

稀な
Meaning
Happening rarely or not often.
Example
He made infrequent visits to his hometown after moving abroad.
彼は海外に移住した後、故郷にあまり頻繁に訪れることはありませんでした。
C1 adjective /ˌɪndɪˈskriːt/

indiscreet

軽率
Meaning
Not careful in what one says or does, likely to reveal secrets or offend.
Example
It was indiscreet of him to mention the plan in public.
公衆の面前で計画について言及するのは軽率だった。
C1 noun /ˌɪndɪˈdʒɛstʃən/

indigestion

Meaning
Discomfort or pain in the stomach associated with difficulty in digesting food.
Example
He avoided spicy food because it often gave him indigestion.
C1 verb /ɪˈluːmɪneɪt/

illuminate

照らす
Meaning
To light up or make something clearer.
Example
Streetlights illuminate the road at night.
街路灯が夜に道路を照らします。
C1 noun /ɪnˈdjuːsmənt/

inducement

誘因
Meaning
something that persuades or encourages someone to do something
Example
The company offered a bonus as an inducement to employees.
会社は従業員にインセンティブとしてボーナスを提供しました。
C1 adjective /ɪnˈvæljʊəbl/

invaluable

計り知れない価値がある
Meaning
Extremely useful or indispensable.
Example
Her advice proved invaluable to my success.
彼女の助言は私の成功にとって非常に貴重でした。
C1 adjective /ɪˈmoʊbəl/

immobile

動けない
Meaning
unable to move or be moved
Example
After the accident, he was immobile for weeks.
事故の後、彼は数週間動けなかった。
C1 adverb /ɪnˈvɜːrs.li/

Inversely

逆に; 反対に
Meaning
in a way that is opposite or contrary; in reverse order or manner
Example
The price of goods is inversely related to their availability in the market.
商品の価格は市場での入手可能性に逆に関連しています。
C1 adjective /ɪˈnɔːrdənət/

inordinate

過度の
Meaning
Excessive or unusually large in degree.
Example
She spent an inordinate amount of time on her phone.
彼女は電話に過度の時間を費やしました。
C1 adjective /ɪnˈdefɪnət/

Indefinite

不確定な
Meaning
not clearly defined; uncertain; vague; unlimited in time
Example
The meeting has been postponed for an indefinite period.
会議は不確定な期間に延期されました。
C1 verb /ɪmˈpɛl/

impel

Meaning
to drive, force, or urge someone to do something
Example
Her curiosity impelled her to open the mysterious box.
C1 noun ˌɪn.ɪˈfɪʃ.ən.si

inefficiency

非効率
Meaning
The state or quality of not achieving maximum productivity; failure to make the best use of time or resources.
Example
Government inefficiency leads to slow project completion.
政府の非効率性がプロジェクトの完了を遅らせる。
C1 noun /ˌɪnflɛksɪˈbɪlɪti/

inflexibility

柔軟性の欠如
Meaning
the quality of being rigid or unwilling to change; lack of adaptability
Example
The inflexibility of the rules caused unnecessary delays.
規則の柔軟性の欠如が不要な遅れを引き起こした。
C1 noun /ˈɪn.trə.vɜːrt/

introvert

内向的
Meaning
A person who tends to be shy and prefers spending time alone rather than in groups.
Example
As an introvert, he preferred reading over attending parties.
内向的な性格として、パーティに参加するよりも読書の方が好きでした。
C1 adjective /ɪˈlɪsɪt/

illicit

不法な
Meaning
Forbidden by law, rules, or custom.
Example
The police shut down the illicit drug operation.
警察は不法な麻薬取引を閉鎖しました。
C1 adjective /ɪnˈsʌf.ər.ə.bəl/

insufferable

耐え難い
Meaning
Too extreme to bear; intolerable.
Example
The heat during the summer was insufferable.
夏の暑さは耐え難かった。
C1 verb /ɪmˈploʊd/

implode

内爆
Meaning
To collapse or burst inward violently.
Example
The old building imploded during the demolition.
古い建物は解体中に内向きに崩壊しました。
C1 adjective /ɪmˈprɒbəbl/

improbable

あり得ない
Meaning
Not likely to be true or to happen.
Example
It seems improbable that he will arrive on time.
彼が時間通りに到着するのはあり得ないようだ。
C1 noun /ˌɪnkjʊˈbeɪʃən/

incubation

卵、細胞、または生物を適切な条件で発展させるプロセス
Meaning
the process of keeping eggs, cells, or organisms in the right conditions for development
Example
The incubation of the eggs lasted for three weeks.
卵のインキュベーションは三週間続きました。
C1 noun /ˌɪm.pəˈzɪʃ.ən/

Imposition

課税; 負担; 不公平な要求
Meaning
the action or process of imposing something or of being imposed; an unfair burden or demand
Example
The imposition of new taxes without consultation angered the citizens greatly.
相談なしに新しい税金が課され、市民は非常に怒りました。
C1 noun /ˈɪnlɛt/

inlet

入り江
Meaning
A small arm of the sea, a lake, or a river; an opening or passage for entry.
Example
The boat entered a narrow inlet along the coast.
船は海岸沿いの狭い入り江に入った。
C1 verb /ɪmˈpɛrɪl/

imperil

危険にさらす
Meaning
To put in danger or at risk.
Example
Reckless driving can imperil the lives of others.
無謀な運転は他人の命を危険にさらす可能性があります。