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A1 noun /aɪˈdiː.ə/

Idea

アイデア; 概念; 提案
Meaning
a thought or suggestion as to a possible course of action; a concept or mental impression
Example
She had a brilliant idea for solving the company's efficiency problem.
彼女は会社の効率問題を解決するための素晴らしいアイデアを持っていました。
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。
C2 noun /ˌɪnkænˈteɪʃən/

incantation

呪文
Meaning
a series of words used as a magic spell or charm
Example
The wizard chanted an incantation to summon the spirits.
魔法使いは霊を呼び出すために呪文を唱えました。
C2 noun /ˈɪsməs/ or /ˈɪsθməs/

isthmus

地峡
Meaning
A narrow strip of land connecting two larger land areas, often with water on either side.
Example
The Panama Canal cuts through the Isthmus of Panama.
パナマ運河はパナマの地峡を通ります。
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 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。
C2 verb /ɪˈnjʊər/

inure

慣れる
Meaning
To become accustomed to something, especially something unpleasant.
Example
Soldiers quickly became inured to the harsh conditions.
兵士たちはすぐに過酷な状況に慣れました。
B2 noun /ɪˈluː.ʒən/

Illusion

幻想
Meaning
a thing that is or is likely to be wrongly perceived or interpreted; a false idea or belief
Example
The magician created a spectacular illusion that made the elephant appear to vanish.
魔術師は壮観な幻想を作り、象が消えるように見えました。
B2 noun /ˈaɪkɒn/

icon

アイコン, 象徴
Meaning
A person or thing regarded as a symbol of something, or a graphic symbol on a screen.
Example
The singer became a cultural icon.
その歌手は文化的なアイコンとなった。
B2 verb /ɪnˈveɪd/

invade

侵入する
Meaning
to enter a place or country forcefully, especially as an enemy
Example
The army invaded the neighboring country.
軍隊は隣国に侵入しました。
C2 noun /ɪmˈprɑːvɪdəns/

improvidence

不注意
Meaning
Lack of foresight or care for future needs.
Example
His improvidence led to financial difficulties.
彼の不注意が彼を財政的な困難に追い込んだ。
C1 adjective /ˌɪndɪˈskrɪmɪnət/

indiscriminate

無差別
Meaning
Done without careful judgment; random or haphazard.
Example
The indiscriminate use of pesticides harms the environment.
農薬の無差別な使用は環境に害を与えます。
C1 noun /ɪnˈsɜːrdʒənt/

insurgent

反乱者
Meaning
A person who rises in revolt against authority or government.
Example
The army arrested several insurgents after the attack.
軍隊は攻撃後、数人の反乱者を逮捕した。
A2 adjective /ˈɪn.dɔːr/

indoor

屋内の
Meaning
situated, occurring, or used inside a building
Example
Indoor plants can improve air quality at home.
屋内の植物は家の空気の質を改善できます。
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 /ˌɪnsərˈmaʊntəbl/

insurmountable

克服不可能
Meaning
Too great to be overcome.
Example
The explorers faced insurmountable odds in the desert.
探検者たちは砂漠で克服不可能な障害に直面した。
B1 noun /ɪnˈstrʌkʃənz/

instructions

指示
Meaning
Detailed information on how something should be done or operated.
Example
Please follow the instructions on the box.
箱に書かれた指示に従ってください。
C1 noun /ˈɪrɪtənt/

irritant

刺激物
Meaning
something that causes irritation or discomfort
Example
Dust is a common irritant for people with allergies.
ほこりはアレルギーを持つ人々にとって一般的な刺激物です。
C1 noun /ɪnˈsɜːrdʒəns/

insurgence

反乱
Meaning
An act of rebellion or uprising against authority.
Example
The government struggled to contain the growing insurgence.
政府は増大する反乱を抑制するのに苦労した。
B1 noun /ˈɪnstrəmənt/

instrument

楽器
Meaning
A tool or device used for a particular purpose, especially for scientific or musical work.
Example
The doctor used a special instrument during the surgery.
医師は手術中に特別な楽器を使用しました。
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 /ˈɪɡ.ni.əs/

igneous

火成
Meaning
Formed through the cooling and solidification of magma or lava.
Example
Granite is an igneous rock commonly used in construction.
花崗岩は建設に一般的に使用される火成岩です。
C1 noun /ɪmˈbæl.əns/

Imbalance

不均衡
Meaning
lack of proportion or relation between corresponding things; unequal distribution
Example
The doctor said the patient's dizziness was caused by an inner ear imbalance.
医者は患者のめまいが内耳の不均衡によって引き起こされたと言いました。
B2 noun /ɪmˈpeɪʃəns/

impatience

忍耐力不足
Meaning
The state of being quickly irritated or unable to wait calmly.
Example
His impatience grew as the meeting dragged on.
会議が長引くにつれて、彼の忍耐力不足が増しました。
B2 adjective /ɪˈreɡjələr/

irregular

不規則な
Meaning
not even or consistent in shape, pattern, time, or behavior; not following normal rules
Example
His attendance at work has been irregular this month.
今月、彼の出勤は不規則だった。
C1 noun /ˈɪmɪnəns/

imminence

差し迫り、間近な状態
Meaning
the state of being about to happen
Example
The imminence of the storm forced people to take shelter.
嵐の差し迫りが人々を避難させることを強制した。
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 adjective /ˈɪrɪtəbl/

irritable

Meaning
easily annoyed or made angry
Example
She became irritable after working long hours without rest.
C2 noun /ɪnˈtɛɡ.jʊ.mənt/

integument

外皮
Meaning
A natural outer covering, such as skin, shell, or rind.
Example
The snake sheds its integument as it grows.
ヘビは成長するにつれて外皮を脱ぎます。
B2 verb /ɪnˈʃʊər/

insure

保険をかける
Meaning
to provide insurance; to make certain
Example
I need to insure my new car.
私は新しい車を保険に入れる必要があります。
C2 adjective /ɪnˈkoʊətɪv/

inchoative

初期の
Meaning
relating to the beginning of something; in an initial stage
Example
The poet used inchoative expressions to depict the dawn of creation.
詩人は創造の夜明けを描くために初期の表現を使いました。
C2 adjective /ˌɪrɛvəˈrɛnʃəl/

irreverential

無礼な
Meaning
Showing a lack of respect for things that are generally taken seriously.
Example
His irreverential humor often shocked traditional audiences.
彼の無礼なユーモアはしばしば伝統的な観客を驚かせました。
C1 noun /ˌɪnklɪˈneɪʃən/

inclination

傾向
Meaning
A natural tendency or urge to act or feel in a particular way.
Example
She has an inclination towards helping others.
彼女は他の人を助ける傾向があります。
A1 preposition /ɪn/

in

中
Meaning
expressing the situation of being enclosed or surrounded by something
Example
She is in the kitchen preparing dinner.
彼女は台所で夕食を準備している。
C2 noun /ˌɪmpjuˈteɪʃən/

imputation

非難
Meaning
an accusation or attribution of blame
Example
The politician denied the imputation of corruption.
政治家は腐敗の非難を否定した。
B2 adjective /ɪnˈstrʌkʃənəl/

instructional

教育的な
Meaning
providing knowledge or information; intended to teach
Example
The website offers many instructional videos for beginners.
このウェブサイトは初心者向けに多くの教育的なビデオを提供しています。
C1 adjective /ɪnˈsɪstənt/

insistent

執拗な
Meaning
demanding something firmly and refusing to accept no
Example
The child was insistent on getting a new toy.
その子供は新しいおもちゃを手に入れることに執拗だった。
B2 adjective /ˈaɪ.dəl/

Idle

怠惰な; 非活動的な; 使われていない
Meaning
lazy; inactive; not working or being used
Example
The factory workers were idle during the strike.
工場の労働者はストライキ中に暇だった。
C2 verb /ˌɪmpɔːrˈtuːn/

importune

しつこく頼む
Meaning
To ask someone persistently or pressingly for something
Example
The child importuned his mother for a new toy.
その子供は新しいおもちゃを欲しがって母親にしつこく頼んだ。
C2 noun /ˌɪnsəˈrɛkʃən/

insurrection

反乱
Meaning
A violent uprising against an authority or government.
Example
The army was called in to suppress the insurrection.
軍隊は反乱を鎮圧するために呼ばれました。
B1 noun /ɪnˈʃʊərəns/

insurance

保険
Meaning
An arrangement by which a company provides compensation for loss, damage, or illness in return for a premium.
Example
He bought health insurance to cover medical expenses.
彼は医療費をカバーするために健康保険に加入しました。
B2 adverb /ɪmˈpɔːtəntli/

importantly

重要な方法で
Meaning
in a way that is of great significance or value
Example
Importantly, the report highlights the need for immediate action.
重要な方法で、報告書は即時の行動の必要性を強調しました。
B2 adjective /ɪnˈklaɪnd/

inclined

傾向がある
Meaning
having a tendency or disposition toward something
Example
He is inclined to help those in need.
彼は困っている人々を助ける傾向がある。
C1 noun /ˈɪtʃ.i.nəs/

itchiness

かゆみ
Meaning
The quality or condition of feeling an irritating sensation on the skin that causes a desire to scratch.
Example
Eye itchiness often leads to rubbing.
目のかゆみはしばしば擦る原因となります。
C2 adjective /ɪnˈæpt/

Inapt

不適切; 不適当
Meaning
not suitable; inappropriate; unfit
Example
His comment was inapt for the formal meeting.
彼のコメントは正式な会議には不適切でした。
A2 adjective, noun /ɪˈtæliən/

italian

幸福
Meaning
relating to Italy, its people, or its language; a person from Italy
Example
She loves Italian food.
彼女は賞を受け取ったとき、自分の幸せを隠せませんでした。
C1 adjective /ɪnˈvɜːs/

Inverse

逆の; 反対の
Meaning
opposite in order, nature, or effect; reversed
Example
There is an inverse relationship between price and demand.
価格と需要の間に逆の関係があります。
B2 verb /ˈɪmɪɡreɪt/

immigrate

移住する
Meaning
to come to live permanently in a foreign country
Example
He immigrated to Canada five years ago.
彼は5年前にカナダに移住しました。
B2 noun /ɪnˈtɛnt/

intent

意図
Meaning
the purpose or reason behind an action; a strong determination to do something
Example
Her intent was to improve the quality of education in the community.
彼女の意図はコミュニティの教育の質を向上させることでした。
C1 noun /ɪnˈdem.nə.ti/

Indemnity

補償
Meaning
security or protection against a loss or other financial burden; compensation for damage or loss
Example
The insurance company provided full indemnity for the damages caused by the flood.
保険会社は洪水による損害に対して完全な補償を提供しました。
C2 adjective /ɪnˈvɪdiəs/

invidious

妬ましい
Meaning
likely to arouse resentment, envy, or anger in others
Example
The manager's invidious remarks created tension among the employees.
マネージャーの妬ましいコメントは、従業員の間に緊張を生み出しました。
C2 adjective /ɪnˈsɪpiənt/

incipient

初期の
Meaning
in an initial stage; beginning to develop
Example
The incipient storm made the sky turn dark and heavy.
初期の嵐が空を暗く重くさせた。
B1 noun /ˌɪntərˈækʃən/

interaction

相互作用
Meaning
The process of people or things acting upon or influencing each other.
Example
The teacher encouraged more interaction between students.
教師は生徒間のさらなるインタラクションを促進しました。
C2 verb /ˌɪntərˈmɪt/

intermit

中断する
Meaning
To suspend or stop for a time; to pause intermittently.
Example
The rain would intermit and then start again.
雨は中断し、再び始まる。
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。
C2 adjective /ɪˈmɪsəbl/

immiscible

不混和
Meaning
Describes liquids that do not mix together.
Example
Oil and water are immiscible liquids.
油と水は不混和の液体です。
C1 noun /ˌɪnkoʊˈhɪrəns/

incoherence

不整合
Meaning
The quality of being unclear, confused, or lacking logical connection.
Example
His speech was full of incoherence and difficult to follow.
彼のスピーチは不整合で、理解するのが難しかった。
C2 adjective /ɪnˈsɛptɪv/

inceptive

初期の
Meaning
Relating to or marking the beginning or initial stage of something.
Example
The inceptive phase of the project was marked by enthusiastic planning.
プロジェクトの開始段階は熱心な計画で特徴づけられました。
C2 adjective /ˌɪndɪˈtɜːrmənət/

indeterminate

不確定
Meaning
Not exactly known, defined, or established; vague or uncertain.
Example
The project was delayed for an indeterminate amount of time.
プロジェクトは不確定な期間に延期されました。
C2 noun /ɪnˈsɪɡniə/

insignia

徽章
Meaning
A badge or symbol that shows rank, position, or membership.
Example
The soldier proudly wore the insignia of his regiment.
兵士は誇らしげに自分の連隊の徽章を身に着けていました。
C2 verb /ɪˈluːmɪn/

illumine

照らす
Meaning
to light up or make clear
Example
The rising sun illumined the mountain peaks.
昇る太陽が山頂を照らした。
C1 adjective /ˌɪrɪˈspɛktɪv/

Irrespective

無視して; 問わず
Meaning
without taking something into account; regardless of
Example
All students will be treated equally, irrespective of their background.
すべての学生は、背景に関係なく平等に扱われます。
B2 noun ɪˈmjuː.nɪ.ti

immunity

免疫力
Meaning
The ability of an organism to resist a particular infection or toxin by the action of specific antibodies.
Example
A strong immunity protects against infections.
強い免疫力は感染症から守ります。
C1 adjective /ˈɪmpətənt/

impotent

無力
Meaning
Lacking power, ability, or strength to take effective action.
Example
The citizens felt impotent against the corrupt system.
市民は腐敗したシステムに対して無力だと感じた。
C2 noun /ɪnˈtɛstəsi/

intestacy

遺言なしで死亡
Meaning
The condition of dying without having made a valid will.
Example
His estate was divided according to the laws of intestacy.
彼の財産は遺言なしでの法則に従って分けられた。
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 /ˈɪm.pæs/

impasse

行き詰まり
Meaning
A situation where no progress is possible.
Example
The negotiations reached an impasse, delaying the agreement.
交渉は行き詰まり、合意が遅れた。
C1 noun /ɪnˈsaɪtmənt/

incitement

扇動
Meaning
the action of provoking unlawful or violent behavior
Example
He was arrested for incitement to riot.
彼は暴動を扇動した罪で逮捕された。
C1 verb /ɪˈnɔːɡjʊreɪt/

inaugurate

Meaning
To formally begin or introduce something, especially with a ceremony.
Example
The mayor will inaugurate the new bridge tomorrow.
C2 noun /ˌɪndɛnˈteɪʃən/

indentation

インデント
Meaning
A space left at the beginning of a line of text; a notch or deep recess on a surface.
Example
The teacher asked the students to use proper indentation in their essays.
先生は学生にエッセイで適切なインデントを使用するように頼みました。
C2 adverb /ɪnˈdjuːbɪtəbli/

indubitably

疑いなく
Meaning
Without a doubt; certainly.
Example
She is indubitably the best candidate for the job.
彼女は疑いなくその仕事の最良の候補者です。
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。
C2 noun /ˌɪnkrʌˈsteɪʃən/

incrustation

硬化層
Meaning
a crust or hard coating formed on the surface of something
Example
The old pipes were blocked due to heavy incrustation of minerals.
古いパイプは鉱物の重い硬化層によって詰まっていました。
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。
C2 noun /ɪmp/

imp

小さないたずら好きな悪魔
Meaning
a small mischievous devil or sprite; a playful troublemaker
Example
The child was acting like a little imp, hiding his toys everywhere.
その子供は小さなインプのように振る舞い、どこにでもおもちゃを隠していました。
C1 adjective ˌɪdiəsɪnˈkrætɪk

idiosyncratic

奇妙で個人的な
Meaning
Relating to idiosyncrasy; peculiar or individual.
Example
His idiosyncratic behavior set him apart from his colleagues.
彼の独特な行動は彼を同僚たちから区別させた。
C2 adjective /ɪnˈdɛkərəs/

indecorous

不作法
Meaning
Not in keeping with good taste and propriety; improper.
Example
His indecorous behavior shocked the audience.
彼の不作法な振る舞いは観客を驚かせた。
B2 noun ˌɪn.fləˈmeɪ.ʃən

inflammation

炎症
Meaning
A localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful.
Example
Chronic inflammation can lead to severe diseases.
慢性炎症は重篤な疾患を引き起こす可能性があります。
C2 adjective /ˌɪnɪkˈspiːdiənt/

inexpedient

不適切
Meaning
Not advisable, suitable, or practical in the circumstances.
Example
It would be inexpedient to invest without proper research.
適切な調査なしで投資することは不適切です。
A2 adverb /ɪˈmiːdiətli/

immediately

直ちに
Meaning
at once; without delay
Example
She responded immediately to the emergency call.
彼女は緊急の電話に直ちに応答した。
C2 verb /ɪnˈveɪɡəl/

inveigle

誘惑する
Meaning
To persuade someone to do something by deception or flattery.
Example
She inveigled him into signing the contract.
彼女は彼に契約書に署名させた。
C2 adjective /ˈɪnfəntaɪl/

infantile

幼稚な
Meaning
characteristic of an infant; childish
Example
His infantile behavior embarrassed everyone at the meeting.
彼の幼稚な行動は会議でみんなを困らせた。
C1 adjective ˈɪn.lənd

Inland

内陸
Meaning
Situated in the interior of a country; away from the coast.
Example
Inland transport boosts local trade.
内陸輸送は地元の貿易を促進します。
B1 adjective ˈɪnəveɪtɪv

innovative

革新的な
Meaning
Featuring new methods; advanced and original
Example
Innovative strategies are required to combat pollution.
革新的な戦略が汚染との戦いに必要です。
C1 adjective /ˌɪnkəmˈpætəbl/

incompatible

互換性がない
Meaning
Not able to exist or work together without conflict.
Example
Their personalities were completely incompatible.
彼らの性格は完全に互換性がなかった。
C1 adjective /ɪmˈpæʃənd/

impassioned

情熱的な
Meaning
Filled with or showing great emotion.
Example
She gave an impassioned speech about human rights.
彼女は人権について情熱的なスピーチを行いました。
C2 noun /ɪnˈtɒksɪkənt/

intoxicant

酔わせる物質
Meaning
a substance, especially alcohol or a drug, that causes intoxication
Example
Alcohol is the most commonly used intoxicant in many cultures.
アルコールは多くの文化で最も一般的に使用される酔わせる物質です。
C1 noun /ɪmˈpɒs.tər/

Impostor

詐欺師; 偽者
Meaning
a person who pretends to be someone else in order to deceive others; a fraud
Example
The impostor convinced everyone he was a doctor until his fake credentials were discovered.
詐欺師は医者だとみんなを納得させましたが、彼の偽の資格が発覚するまでそれが続きました。
C1 verb /ɪnˈsɪnjueɪt/

insinuate

Meaning
To suggest or hint something indirectly and often unpleasantly.
Example
He insinuated that she had lied about her qualifications.
C2 verb /ɪnˈsteɪt/

instate

任命する
Meaning
To set up in position, office, or authority.
Example
The board decided to instate her as the new director.
取締役会は彼女を新しいディレクターにインステイトすることを決定しました。
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 /ˈɪŋ.krə.mənt/

Increment

増加
Meaning
an increase or addition, especially one of a series on a fixed scale; a regular increase in salary
Example
He received an annual increment of five percent in his salary this year.
彼は今年、自分の給料に5パーセントの年次増加を受け取った。
C1 adjective /ɪnˈsɛnsəbl/

insensible

無意識
Meaning
Unconscious; unaware of or indifferent to something.
Example
He was insensible to the cold as he lay in the snow.
彼は雪の中で横たわっているとき、寒さに無意識でした。
C1 adjective /ɪˈnɛpt/

inept

不器用
Meaning
lacking skill or ability; clumsy or incompetent
Example
His inept handling of the situation made it worse.
彼の不器用な状況の対処が状況を悪化させた。
C1 adjective /ɪˈmuː.və.bəl/

immovable

動かせない
Meaning
Not able to be moved; fixed in position.
Example
Immovable barriers prevent change.
動かせない障害物が変化を妨げる。
B1 noun ɪmˈpruːv.mənts

improvements

改善
Meaning
The action of making or becoming better; an instance of something becoming or being made better.
Example
Continuous improvements increase productivity.
継続的な改善は生産性を高めます。
A2 adverb /ˌɪnˈdɔːrz/

indoors

屋内で
Meaning
inside a building; within an enclosed space
Example
Because of the rain, everyone stayed indoors.
雨のため、みんな屋内で過ごしました。
C2 adjective /ɪnˈsuːpərəbl/

insuperable

克服できない
Meaning
Impossible to overcome or surpass.
Example
The team faced insuperable challenges during the expedition.
チームは遠征中に克服できない課題に直面しました。
C1 noun /ɪˌluːmɪˈneɪʃən/

illumination

Meaning
the act of lighting something or making something clear
Example
The street was filled with bright illumination from the lamps.
C1 noun /ɪnˈædɪkwəsi/

inadequacy

不十分さ
Meaning
lack of sufficient ability, quality, or strength; a feeling of not being good enough
Example
She struggled with feelings of inadequacy at work despite her strong qualifications.
十分な資格があるにもかかわらず、彼女は職場で不十分さを感じていた。
B2 verb /ˈɪntɪɡreɪt/

integrate

統合する
Meaning
To combine or bring together into a unified whole.
Example
The new system integrates data from multiple sources.
新しいシステムは複数のソースからデータを統合します。
C2 adjective /ɪnˈtræn.sɪ.dʒənt/

intransigent

頑固な, 譲らない, 固執した
Meaning
Unwilling or refusing to change one's views or to agree about something.
Example
His intransigent stance delayed the agreement.
彼の頑固な態度が合意を遅らせました。
B2 verb /ɪnˈsʌlt/

insult

侮辱する
Meaning
to speak or act in a way that hurts someone's feelings or shows disrespect
Example
He felt insulted by her rude comments.
彼は彼女の失礼なコメントで侮辱されたと感じた。
C2 adjective /ɪˈlɪmɪtəbl/

illimitable

無限
Meaning
Without limits or bounds.
Example
The universe is often described as illimitable.
宇宙はしばしば無限であると説明されます。
B1 noun /ˈɪnstəns/

instance

例
Meaning
An example or single occurrence of something.
Example
This is just one instance of his generosity.
これは彼の寛大さの一例です。
C2 noun /ɪˈrʌp.ʃən/

Irruption

突然の暴力的な侵入; 侵略または襲撃; 突然の噴出または噴火
Meaning
a sudden violent entry; an invasion or raid; a sudden outburst or eruption
Example
The army's irruption into enemy territory caught the opposing forces completely off guard.
軍隊の敵領土へのイラプションは、相手の力を完全に不意を突いた。
C1 adjective /ˌɪndɪˈvɪzəbl/

indivisible

Meaning
Not able to be divided or separated.
Example
The country's unity was indivisible despite differences.
C1 adjective /ˈɪnsjələr/

insular

狭い心の、島に関連する
Meaning
Narrow-minded, isolated, or relating to an island.
Example
The community was criticized for its insular attitudes toward outsiders.
そのコミュニティは外部の人々に対する狭量な態度で批判されました。
C2 noun /ɪˈnænɪti/

inanity

馬鹿げたこと, 空虚
Meaning
a nonsensical remark or action; silliness; emptiness
Example
The speech was full of inanities that bored the audience.
スピーチは聴衆を退屈させる馬鹿げたことだらけだった。
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 /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 /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。
C2 adjective /ɪmˈpælpəbəl/

impalpable

触れない
Meaning
unable to be felt by touch; difficult to grasp or understand
Example
There was an impalpable sense of fear in the room.
部屋には触れない恐怖感があった。
C1 adjective /ˌɪnəˈfɛnsɪv/

inoffensive

無害な
Meaning
Not likely to offend or provoke; harmless.
Example
His inoffensive remarks kept the conversation friendly.
彼の無害なコメントは会話を友好的に保ちました。
C2 noun /ˌɪmprɪˈkeɪʃən/

imprecation

呪い
Meaning
A spoken curse or expression of strong condemnation.
Example
The angry crowd hurled imprecations at the corrupt official.
怒った群衆は腐敗した役人に呪いを投げかけた。
B2 verb /ɪnˈflɪkt/

inflict

加える
Meaning
to cause something unpleasant or painful to be suffered by someone or something
Example
The storm inflicted considerable damage to the city.
嵐は都市にかなりの被害を与えました。
B2 verb /ˈaɪ.sə.leɪt/

isolate

隔離する
Meaning
To separate something or someone from others.
Example
Doctors tried to isolate the patient to prevent the spread of infection.
医師たちは感染の拡大を防ぐために患者を隔離しようとしました。
A1 preposition /ˈɪntuː/

into

中へ
Meaning
expressing movement or direction to the inside of something
Example
She walked into the room quietly.
彼女は静かに部屋に入った。
C2 noun /ˌɪnəməˈrɑːtə/

inamorata

Meaning
A woman with whom someone is in love; a female lover.
Example
He wrote a poem dedicated to his inamorata.
C2 verb /ˌɪnkəˈpæsɪteɪt/

incapacitate

無力化する
Meaning
to deprive someone or something of the ability or strength to function
Example
The severe injury incapacitated the player for the rest of the season.
その重傷はプレーヤーをシーズンの残りの期間無力化させた。
C2 noun /ˌɪnvəˈlɪdɪti/

invalidity

無効性
Meaning
the state of being invalid, legally void, or lacking force or validity
Example
The court ruled that the contract suffered from invalidity.
裁判所はその契約に無効性があると判断した。