infantile
All a b c d e f g h i j k l m n o p q r s t u v w x y z
All CEFR A1 A2 B1 B2 C1 C2
Content locale
EN 英語 BN ベンガル語 HI ヒンディー語 ES スペイン語 FR フランス語 DE ドイツ語 RU ロシア語 ZH 中国語 JA 日本語
All Vocabulary Cards All Vocabularies
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。
B1 noun ɪnˈven.ʃən

invention

発明
Meaning
The action of inventing something, typically a process or device.
Example
The invention revolutionized communication.
その発明はコミュニケーションを革命的に変えました。
C2 noun /ˌɪlɪbəˈræləti/

illiberality

不寛容
Meaning
The quality of being illiberal; lack of tolerance or generosity.
Example
The illiberality of the new laws alarmed the citizens.
新しい法律の不寛容が市民を驚かせました。
B2 noun /ɪnˌtɜːrprəˈteɪʃən/

interpretation

解釈
Meaning
the action of explaining the meaning of something
Example
The teacher gave her own interpretation of the poem.
教師は詩の自分の解釈を示しました。
C1 adjective /ˌɪnɪkˈskjuːzəbl/

inexcusable

許しがたい
Meaning
Too bad to be justified or overlooked; unforgivable.
Example
His rude behavior was inexcusable.
彼の無礼な行動は許しがたいものでした。
C2 adjective /ɪmˈpruːdənt/

imprudent

不注意な
Meaning
Not showing care for the consequences of an action.
Example
It was imprudent to drive in such stormy weather.
こんな嵐の天気で運転するのは不注意だった。
C1 verb ɪˈmɜːrs

immerse

浸る
Meaning
To involve oneself deeply in a particular activity or interest; to surround completely.
Example
Immerse yourself in the new language.
新しい言語に浸ってください。
A1 noun /aɪs/

Ice

Meaning
water that has frozen and become solid
Example
The ice in my drink melted quickly in the hot weather.
私の飲み物の氷は暑い天気で素早く溶けました。
C1 adjective /ˌɪnədˈvɜːrtənt/

inadvertent

意図しない, 不注意な
Meaning
Not resulting from or achieved through deliberate planning; unintentional.
Example
Her inadvertent mistake caused a delay in the project.
彼女の不注意なミスがプロジェクトの遅延を引き起こしました。
C2 noun /ˈɪrɪtənsi/

irritancy

苛立ち
Meaning
the quality or state of causing irritation; legal or formal invalidation
Example
The constant noise became an irritancy to the neighbors.
絶え間ない騒音は隣人にとって苛立ちの原因となりました。
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。
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。
C1 adjective /ɪnˈsɪdiəs/

insidious

陰険な
Meaning
Proceeding in a gradual, subtle way but with harmful effects.
Example
The insidious spread of misinformation can damage trust.
誤った情報の陰険な広がりは信頼を傷つける可能性がある。
A1 conjunction /ɪf/

if

もし
Meaning
used to introduce a condition or supposition
Example
If it rains tomorrow, we will stay home.
もし明日雨が降ったら、私たちは家にいます。
C2 verb /ˈɪŋkʌlpeɪt/

inculpate

非難する
Meaning
To blame or accuse someone of wrongdoing.
Example
The evidence seemed to inculpate the suspect in the crime.
証拠は容疑者を犯行に巻き込んでいるように見えた。
B1 adjective /ɪnˈtɜːrnəl/

internal

内部
Meaning
situated inside; relating to the inside or inner part of something
Example
The company is conducting an internal audit this month.
その会社は今月内部監査を行っています。
C2 noun /ˌɪmbəˈsɪləti/

imbecility

愚かさ
Meaning
Extreme foolishness, stupidity, or weakness of mind.
Example
The plan was abandoned due to its sheer imbecility.
その計画はその愚かさから放棄されました。
C1 adjective /ɪnˈvɑːlənˌtɛri/

involuntary

不随意
Meaning
done without will or conscious control
Example
He gave an involuntary shiver when he heard the loud noise.
彼は大きな音を聞いたとき、不随意に震えた。
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 verb /ˌɪntərˈsiːd/

intercede

Meaning
to act or plead on behalf of someone in difficulty or trouble; to intervene between parties to help resolve a dispute
Example
She interceded with the teacher to give her brother another chance.
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 verb /ɪnˈklaɪn/

incline

傾く
Meaning
to feel willing or favorably disposed toward something; to bend or tilt
Example
She is inclined to agree with the proposal.
彼女は提案に賛成する傾向があります。
B2 noun /ɪnˈdʌstriəl ˌrɛvəˈluːʃən/

Industrial Revolution

産業革命
Meaning
The rapid development of industry that occurred in Britain in the late 18th and 19th centuries, brought about by the introduction of machinery and characterized by the use of steam power and the growth of factories.
Example
The Industrial Revolution marked a shift in production processes.
産業革命は生産プロセスにおける変化を示しました。
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 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。
B1 noun /ˈɪnstəns/

instance

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。
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。
B2 noun ˌɪmplɪmenˈteɪʃən

implementation

実行
Meaning
The process of putting a decision or plan into effect; execution.
Example
Proper implementation of policies is crucial.
方針の適切な実行は重要です。
C2 verb /ɪmˈpjuːt/

impute

帰する
Meaning
to attribute a fault or responsibility to someone
Example
They imputed the company's success to good leadership.
彼らは会社の成功を良いリーダーシップに帰属させた。
C2 adjective /ɪnˈkoʊ.ɪt/ or /ɪnˈkoʊ.eɪt/

inchoate

未完成
Meaning
Just begun and not fully formed; rudimentary.
Example
His inchoate ideas needed more research to be developed.
彼の未完成のアイデアは、さらに開発するためにもっと研究が必要だった。
C2 adjective /ˌɪntərˈniːsaɪn/

internecine

内部紛争
Meaning
Relating to conflict within a group, often causing mutual destruction.
Example
The internecine conflict weakened the organization from within.
内部紛争は組織を内部から弱体化させた
C2 noun /ˌɪnədˈvɜːrtəns/

inadvertence

不注意
Meaning
Failure to pay attention; carelessness.
Example
The error happened through sheer inadvertence.
エラーは単なる不注意で発生しました。
C2 verb /ɪˈniː.bri.eɪt/

inebriate

Meaning
to intoxicate; to make someone drunk
Example
The strong wine was enough to inebriate even the most experienced drinker.
C2 adjective /ɪˈmɒdərət/

immoderate

過度な
Meaning
excessive; beyond reasonable limits
Example
He has an immoderate love for sweets.
彼はお菓子に対して過度の愛情を持っています。
C2 adjective /ɪnˈɡreɪʃiˌeɪtɪŋ/

ingratiating

お世辞を言う
Meaning
Charming or flattering in a way intended to gain favor.
Example
His ingratiating smile made everyone trust him quickly.
彼のお世辞を言う笑顔は、すべての人々に彼を素早く信頼させた。
C1 adjective /ɪnˈdʌstriəs/

industrious

勤勉な
Meaning
Hardworking and diligent in one's duties.
Example
She is an industrious student who always completes her assignments on time.
彼女は常に期限通りに課題を終わらせる勤勉な学生です。
C2 noun /ˈɪɡ.nəˌmɪn.i/

ignominy

恥辱
Meaning
Public shame, disgrace, or dishonor.
Example
He lived the rest of his life in ignominy after the scandal.
スキャンダル後、彼は生涯を恥辱の中で過ごした。
B1 adverb /ɪˈnɪʃəli/

initially

最初に
Meaning
At the beginning; at first.
Example
Initially, he refused the offer but later accepted it.
最初に、彼はその提案を断ったが、後で受け入れた。
B2 adjective /ˌɪn.trəˈdʌk.tər.i/

introductory

導入の
Meaning
Serving as an introduction; preliminary or preparatory.
Example
The professor gave an introductory lecture on economics.
教授は経済学についての導入の講義を行いました。
B1 verb ˈɪndɪkeɪts

indicates

示す
Meaning
Point out; show; be a sign or symptom of; suggest as a desirable or necessary course of action.
Example
The rising trend indicates an urgent need for action.
上昇している傾向は、行動が急務であることを示しています。
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。
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。
C2 noun /ˈɪndɪkənt/

indicant

指標
Meaning
Something that indicates or points to a fact or condition.
Example
High fever is often an indicant of infection.
高熱はしばしば感染の指標となります。
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 /ɪnˌtɪmɪˈdeɪʃən/

intimidation

威圧
Meaning
The action of frightening or threatening someone to make them do something.
Example
The workers reported cases of intimidation by the management.
労働者たちは経営陣による威圧の事例を報告しました。
C2 noun /ɪmˌpɜːrtərbəˈbɪləti/

imperturbability

不動心
Meaning
The quality of being calm and not easily disturbed or upset.
Example
Her imperturbability during the crisis impressed everyone.
危機の際に彼女の不動心は皆に印象を与えました。
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 adjective /ˌɪnsəˈluːbriəs/

insalubrious

不健康
Meaning
Unhealthy or not conducive to well-being.
Example
They moved out of the insalubrious neighborhood for the sake of their health.
彼らは健康のために不健康な地域から引っ越しました
C2 noun /ˈaɪdlər/

idler

怠け者
Meaning
A person who avoids work or spends time lazily.
Example
He was known as an idler who wasted his days.
彼は自分の時間を無駄にするアイドラーとして知られていました。
C1 adjective /ɪnˈkɒŋɡruəs/

incongruous

不調和
Meaning
Not fitting in with or suitable for the surroundings.
Example
His jokes were incongruous during the serious meeting.
彼の冗談は真面目な会議では不調和だった。
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。
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。
B1 verb /ˌɪntəˈrʌpt/

interrupt

割り込む
Meaning
to stop someone from speaking or doing something by suddenly saying or doing something
Example
She tried not to interrupt while he was speaking.
彼女は彼が話している間、割り込まないようにした。
C2 noun /ˌɪn.strəˈmɛn.təl.ɪst/

instrumentalist

楽器奏者
Meaning
A person who plays a musical instrument.
Example
The instrumentalist played a beautiful solo on the violin.
楽器奏者はバイオリンで美しいソロを演奏しました。
B1 noun ɪˈnɪʃətɪv

initiative

イニシアティブ
Meaning
An act or strategy intended to resolve a difficulty or improve a situation; a fresh approach to something.
Example
NASA's initiative to return humans to the Moon is ambitious.
NASAの月面への人類を戻すイニシアティブは野心的です。
B2 noun /ɪnˈtɛnsəti/

intensity

強度
Meaning
The quality of being extreme, strong, or forceful in degree.
Example
The intensity of the storm frightened the villagers.
嵐の強度は村人たちを驚かせた。
C1 adjective /ɪˈræʃənəl/

irrational

非合理的
Meaning
not logical or reasonable; lacking clear thought
Example
His fear of the dark was completely irrational.
彼の暗闇への恐れは完全に非合理的でした。
A2 noun/adjective /ˌɪndɪˈvɪdʒuəl/

individual

個人
Meaning
A single human being as distinct from a group; relating to one person.
Example
Each individual has the right to freedom of speech.
各個人には表現の自由がある。
B2 noun /ɪnˈfek.ʃən/

Infection

感染
Meaning
the process of infecting or the state of being infected; a disease caused by germs
Example
The doctor prescribed antibiotics to treat the bacterial infection in her throat.
医師は彼女の喉の細菌感染を治療するために抗生物質を処方しました。
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。
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 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。
A2 verb /ɪɡˈnɔːr/

ignore

無視する
Meaning
to refuse to take notice of; to disregard intentionally
Example
She decided to ignore the rude comments.
彼女は失礼なコメントを無視することに決めました。
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。
C2 adjective /ɪnˈsuːsiənt/

insouciant

無頓着
Meaning
Showing a casual lack of concern; carefree.
Example
He gave an insouciant shrug and walked away.
彼は無頓着に肩をすくめて、歩き去った。
C1 adjective ɪnˈdʒiː.ni.əs

ingenious

独創的
Meaning
Showing inventiveness and skill; clever, original, and inventive.
Example
His ingenious ideas transformed modern physics.
彼の独創的なアイデアは現代物理学を変えました。
C2 adjective /ˈɪm.pi.əs/

Impious

不敬な; 冒涜的
Meaning
irreligious; lacking reverence for religion; blasphemous
Example
The impious act shocked the religious community.
不敬な行為は宗教コミュニティを驚かせました。
B2 adjective /ˈɪmpæktfʊl/

impactful

インパクトがある
Meaning
Having a major impact or effect; powerful and forceful.
Example
Her impactful speech moved the audience to take action.
彼女のインパクトのあるスピーチは、聴衆を行動に駆り立てた。
B2 noun /ɪnˈspɛktər/

inspector

検査官
Meaning
An official employed to ensure regulations are obeyed or standards are met.
Example
The inspector carefully checked the restaurant's kitchen for hygiene standards.
検査官はレストランのキッチンを衛生基準に従って慎重に確認しました。
C1 adjective /ˌɪndɪˈstɪŋkt/

indistinct

不明瞭な
Meaning
Not clear or sharply defined; vague or blurred.
Example
The sound of voices was indistinct in the distance.
遠くからの声は不明瞭でした。
B2 adjective/noun /ɪˈrɑːki/

iraqi

イラクの
Meaning
relating to Iraq or its people
Example
The Iraqi culture is rich and diverse.
イラクの文化は豊かで多様です。
C2 adjective /ɪnˈsɛndiˌɛri/

incendiary

扇動的な / 挑発的な
Meaning
designed to cause fires or stir up conflict
Example
The politician’s incendiary remarks angered the crowd.
政治家の挑発的な発言が群衆を怒らせた。
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。
B2 verb /ɪnˈkwaɪər/

inquire

尋ねる
Meaning
to ask; to investigate
Example
She inquired about the job opening.
彼女は仕事の募集について尋ねました。
C2 adjective /ɪmˈplaɪəbl/

impliable

暗示可能な
Meaning
Capable of being implied or suggested.
Example
The meaning of the statement is not directly clear but is impliable from the context.
その声明の意味は直接的には明確ではないが、文脈から推測可能である。
C2 noun /ɪnˈkwɪzɪtər/

inquisitor

尋問者
Meaning
A person who asks many questions, often in an official or harsh manner.
Example
The inquisitor demanded detailed answers from the witness.
尋問者は証人から詳細な回答を要求しました。
B2 verb /ɪmˈprɪzən/

imprison

投獄する
Meaning
to put someone in prison; to confine or restrict someone's freedom
Example
The judge imprisoned the criminal for five years.
裁判官は犯罪者を5年間投獄しました。
C2 noun /ˈɪmpjʊdəns/

impudence

厚かましさ
Meaning
Rude and disrespectful behavior.
Example
The student's impudence shocked the entire class.
その学生の厚かましさはクラス全体を驚かせた。
C2 noun /ɪnˈɡrætɪˌtjuːd/

ingratitude

恩知らず
Meaning
Lack of gratitude; failure to show thanks or appreciation.
Example
His ingratitude hurt her feelings after all she had done for him.
彼の恩知らずは、彼女が彼のために多くのことをした後、彼女の気持ちを傷つけた。
C2 noun /ˌɪnsjəˈlærəti/

insularity

島国性
Meaning
The state of being isolated or narrow-minded.
Example
The insularity of the group prevented them from accepting new ideas.
グループの島国性は新しいアイデアを受け入れることを妨げた。
C1 verb /ˈɪmplɪˌkeɪt/

implicate

関与する
Meaning
To show someone’s involvement in a crime or wrongdoing.
Example
The evidence implicated several officials in the scandal.
証拠はスキャンダルに関与した何人かの職員を示した。
B2 verb /ɪnˈtriːɡ/

intrigue

魅了する
Meaning
to arouse curiosity or interest; to make someone fascinated
Example
The mystery novel will intrigue any reader.
ミステリー小説はすべての読者を魅了するでしょう。
B2 verb /ˈɪmɪteɪt/

imitate

真似る
Meaning
to copy the behavior or manner of someone or something
Example
Children often imitate their parents' behavior.
子供たちはしばしば親の行動を真似します。
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 noun /ɪnˈfɜː.mə.ti/

Infirmity

虚弱; 病気; 衰弱
Meaning
physical or mental weakness; a disease or ailment; frailty
Example
Despite his advanced age and various infirmities, he remained mentally sharp and alert.
高齢で多くの病気を抱えていても、彼は精神的に鋭く、警戒心を持ち続けました。
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。
A1 pronoun /aɪ/

i

Meaning
used by a speaker to refer to himself or herself
Example
I am learning English every day.
私は毎日英語を学んでいます。
C1 noun ˌɪndɪˈspensəbl̩ ˈkɒmpɪtənsi

indispensable competency

不可欠な能力
Meaning
Essential skill or ability that cannot be done without; a crucial capability that is absolutely necessary.
Example
Digital literacy is an indispensable competency in the 21st century.
デジタルリテラシーは21世紀のインディスペンセブルなコンピテンスです。
B2 noun, verb /ɪntʃ/

inch

インチ / ゆっくり動く
Meaning
A unit of length equal to 2.54 centimeters; or to move slowly and carefully in small amounts.
Example
She inched closer to the edge of the stage.
彼女はステージの端にゆっくり近づいた。
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。
B2 adjective /aɪˈrɒnɪkəl/

ironical

皮肉な
Meaning
expressing irony; having the nature of irony
Example
Her ironical tone made everyone uncomfortable.
彼女の皮肉な口調は、皆を不快にさせました。
C1 adjective ɪnˈsaɪ.sɪv

incisive

鋭い
Meaning
Intelligently analytical and clear-thinking; showing clear thought and good understanding of what is important.
Example
His incisive comments revealed the core issues.
彼の鋭いコメントは核心的な問題を明らかにしました。
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。
C1 adjective /ɪnˈvɛntɪv/

inventive

創造的
Meaning
Having the ability to create or design new things or to think originally.
Example
The inventor was known for his inventive solutions to everyday problems.
発明家は日常の問題に対する創造的な解決策で知られていた。
C1 adjective, noun /ˈɪnvəlɪd/ (adjective), /ɪnˈvælɪd/ (noun)

invalid

無効
Meaning
Not valid; having no force or effect. Also refers to a person too weak or ill to care for themselves.
Example
The court declared the contract invalid.
裁判所は契約を無効と宣言した。
C1 noun /ˌɪn.trəˈspek.ʃən/

introspection

内省
Meaning
The examination or observation of one's own mental and emotional processes; self-reflection.
Example
Through introspection, she gained insight into her emotions.
内省を通じて、彼女は自分の感情に対する深い洞察を得ました。
A2 verb /ɪnˈvaɪtɪd/

invited

招待された
Meaning
asked someone formally or politely to go somewhere or do something
Example
She was invited to the party.
彼女はパーティーに招待された。
B1 noun /ɪnˈtɛnʃən/

intention

意図
Meaning
A plan, aim, or purpose behind an action.
Example
Her intention was to finish the project before the deadline.
彼女の意図はプロジェクトを締め切り前に終わらせることだった。
B2 noun /ˈɪnfənt/

infant

乳児
Meaning
A very young child or baby.
Example
The infant was sleeping peacefully in the cradle.
乳児はゆりかごで静かに眠っていました。
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.
C2 adjective /ɪnˈɛstɪməbl/

inestimable

計り知れない
Meaning
Too great or valuable to be measured or estimated.
Example
Her contribution to the project was of inestimable value.
プロジェクトへの彼女の貢献は計り知れない価値があった。
B2 verb /ˌɪntərˈfɪər/

interfere

幸せ
Meaning
to become involved in something that is not your concern; to hinder or obstruct
Example
Parents should not interfere in their children’s personal choices.
彼女は賞を受け取ったとき、自分の幸せを隠すことができませんでした。
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。
B2 adjective aɪˈkɒnɪk

iconic

象徴的な
Meaning
Very famous or popular, especially being considered to represent particular opinions or a particular time.
Example
The line "It was the best of times..." is iconic.
"それは最良の時代だった…"というセリフは象徴的です。
C1 noun /ɪnˈtɛstɪn/

intestine

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 adverb /ˌɪnsɪˈdɛntəli/

incidentally

ちなみに
Meaning
by the way; used to introduce a remark not directly related to the main subject
Example
Incidentally, did you know that she studied in Paris?
ちなみに、彼女がパリで勉強していたことを知っていましたか?
B1 adjective /ɪˈliː.ɡəl/

illegal

違法
Meaning
Not allowed by law; unlawful.
Example
It is illegal to drive without a valid license.
有効な免許なしで運転することは違法です。
B2 noun /ˈɪnˌteɪk/

intake

摂取
Meaning
the process of taking something in, especially food or drink
Example
He monitored his daily intake of calories to maintain a healthy diet.
彼は健康的な食事を維持するために毎日のカロリー摂取量を監視しました。
C1 adjective /ˌɪn.səbˈstæn.ʃəl/

insubstantial

不十分な
Meaning
Lacking strength, substance, or solidity.
Example
The evidence provided was insubstantial and unconvincing.
提供された証拠は不十分で説得力がなかった。
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。
C1 noun /ˈɪŋklɪŋ/

inkling

予感
Meaning
A slight idea, hint, or suspicion about something.
Example
She had an inkling that he was planning a surprise.
彼女は彼がサプライズを計画しているという予感を持っていた。
B1 noun ɪnˈvestmənt

investment

投資
Meaning
The action or process of investing money for profit or material result.
Example
Investment in waste management infrastructure is essential.
廃棄物管理インフラへの投資は不可欠です。
C1 verb /ɪɡˈnaɪt/

ignite

点火する
Meaning
To catch fire or cause to catch fire; to start or arouse.
Example
The sparks ignited the dry leaves in seconds.
火花が数秒で乾燥した葉に火をつけた。
C2 adjective /ɪmˈprɛɡnəbl̩/

impregnable

攻略不可能
Meaning
Unable to be captured, broken into, or defeated.
Example
The fortress was considered impregnable by the enemy.
その要塞は敵によって攻略不可能と見なされていました。
C2 noun /ˌɪntərˈlɒkjətər/

interlocutor

対話者
Meaning
a person who takes part in a conversation or dialogue
Example
She was a skilled interlocutor during the debate.
彼女は討論中に優れた対話者でした。
C1 adjective /ɪnˈtɒl.ər.ə.bəl/

Intolerable

耐えられない
Meaning
unable to be endured; extremely unpleasant or painful
Example
The noise from the construction site was intolerable.
工事現場の騒音は耐えられないほどひどかった。
C2 verb /ɪnˈdɛmnɪfaɪ/

indemnify

Meaning
to compensate someone for harm or loss; to secure against future damage or cost
Example
The insurance company agreed to indemnify the client for the damages.
B1 adjective /ˈɪrɪteɪtɪŋ/

irritating

いらいらさせる
Meaning
causing annoyance, impatience, or mild anger
Example
The constant noise from the street is extremely irritating.
通りからの絶え間ない騒音はいらいらさせる。
C1 noun /ɪmˈpɜː.mə.nəns/

impermanence

無常
Meaning
The state or fact of lasting for only a limited period of time.
Example
The philosophy of Buddhism emphasizes the impermanence of life.
仏教の哲学は、人生の無常性を強調します。
C1 noun /ˈɪnˌmeɪt/

inmate

囚人
Meaning
a person confined to an institution such as a prison or hospital
Example
The prison has over a thousand inmates.
刑務所には千人以上の囚人がいます。
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。