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B2 adjective-na #6,500 le plus courant 8 min de lecture

脆弱

zeijaku Top 6,500

Entraîne-toi Exemples Notes et astuces 脆弱 en 30 secondes

Explication 脆弱 in your Level:

At the A1 level, '脆弱' (zeijaku) is a very difficult word that you usually don't need to use. However, you can think of it as a 'super-formal' way to say 'weak' (yowai). Imagine a toy that breaks very easily because it was made poorly. In A1 Japanese, you would just say 'yowai' (weak). But if you were a scientist or a computer expert, you might use 'zeijaku.' It's like the difference between saying 'The wall is weak' and 'The wall's structure is vulnerable.' For now, just remember that if you see this word, it means something is not strong and might break or have a problem soon. It's often used for computer security, so if you see it on your phone or computer, it might mean you need to update your software to stay safe.

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At the A2 level, you are starting to learn more specific adjectives. While 'yowai' (weak) is your go-to word, '脆弱' (zeijaku) is a word you might see in news headlines or on safety signs. It is a 'na-adjective,' so you use it like 'zeijaku na' + noun. For example, 'zeijaku na tatemono' means a 'fragile building.' You should recognize this word when reading about the environment or technology. It implies that something is weak in a way that is dangerous or risky. If a bridge is 'zeijaku,' you probably shouldn't drive a heavy truck over it. It's a formal word, so you don't use it with your friends, but you will see it in books and on the internet.

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At the B1 level, you should begin to distinguish between different types of 'weakness.' '脆弱' (zeijaku) is specifically for structural, systemic, or technical vulnerability. You will frequently encounter the noun form '脆弱性' (zeijakusei), which means 'vulnerability.' In the context of the internet, this is the word for a security hole. If you are describing a plan or a social system that is easily broken by outside events, 'zeijaku' is the perfect formal choice. Unlike 'moroi' (which is more about physical brittleness or emotions), 'zeijaku' is objective and often used in professional reports. You should be able to understand it in news broadcasts and start using it in formal writing or presentations when discussing risks.

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At the B2 level, '脆弱' (zeijaku) is a key vocabulary item. You are expected to use it accurately in professional and academic contexts. It describes a state where an entity (a system, an economy, a building, or a social group) lacks the resilience to withstand external shocks. You should understand its nuances compared to 'kyojaku' (physical frailty) and 'nanjaku' (softness/weakness of will). In business, you might use it to describe a '脆弱なビジネスモデル' (a vulnerable business model). In social science, you would use '脆弱な立場' (vulnerable position) to describe marginalized groups. Mastering the collocations of 'zeijaku'—such as 'zeijakusei o kokufuku suru' (overcome vulnerability)—is essential for achieving fluency in formal Japanese.

At the C1 level, you should appreciate the philosophical and critical nuances of '脆弱' (zeijaku). It is often used in high-level discourse to analyze the inherent instabilities of modern civilization, financial markets, or ecological systems. You will see it in complex phrases like 'サイバー空間の脆弱性' (vulnerabilities of cyberspace) or '地政学的な脆弱性' (geopolitical vulnerability). At this level, you should be able to debate the 'zeijakusei' of various structures, using it to point out deep-seated flaws that aren't immediately obvious. You should also be comfortable with its use in literature or advanced journalism where it might describe the 'fragility of human existence' (人間存在の脆弱性), moving beyond technical contexts into more abstract, existential realms.

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At the C2 level, '脆弱' (zeijaku) is a tool for precise, nuanced analysis. You understand that the word carries a weight of 'structural inevitability'—that the weakness is built into the very design of the subject. You can use it to critique complex systems, such as 'アルゴリズムの脆弱性を突く' (exploiting the vulnerabilities of an algorithm) or 'グローバル・サプライチェーンの脆弱性が露呈した' (the vulnerabilities of the global supply chain were exposed). You are also aware of its historical and kanji-based nuances, recognizing how the 'brittleness' of '脆' combines with the 'weakness' of '弱' to create a specific image of systemic failure. At this level, your usage of 'zeijaku' and its related compounds is indistinguishable from that of a highly educated native speaker, used with perfect register and context.

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Entraîne-toi Exemples Notes et astuces

脆弱 en 30 secondes

脆弱 (zeijaku) is a formal Japanese word meaning fragile, weak, or vulnerable, used primarily for systems and structures.
It is a na-adjective (脆弱な) and is the root of the noun 脆弱性 (zeijakusei), meaning 'vulnerability.'
Commonly found in IT (security flaws), economics (fragile markets), and environmental contexts (vulnerable ecosystems).
Distinguish it from 弱い (yowai - general weak) and 脆い (moroi - physically brittle or emotionally sensitive).

The Japanese word 脆弱 (ぜいじゃく - zeijaku) is a sophisticated na-adjective that describes a state of being fragile, weak, or highly susceptible to damage. While the English word 'weak' can be translated as the simple 'yowai' (弱い), zeijaku carries a more formal, technical, and systemic nuance. It suggests a structural or inherent flaw that makes an entity vulnerable to external pressure or attack. In the modern era, you will encounter this word most frequently in the context of cybersecurity, where it refers to 'vulnerabilities' in software or networks.

Structural Fragility: This refers to physical objects or systems that lack the robustness to withstand stress. For example, an old building with a zeijaku foundation is at high risk during an earthquake.
Information Technology (IT): Used as 脆弱性 (zeijakusei), it translates directly to 'vulnerability.' It describes a bug or misconfiguration that hackers can exploit.
Societal or Economic Weakness: It describes economies or social safety nets that are easily disrupted by global crises, such as a pandemic or a market crash.

このシステムのセキュリティは非常に脆弱であり、早急な対策が必要です。(Kono shisutemu no sekyuriti wa hijyō ni zeijaku de ari, sōkyū na taisaku ga hitsuyō desu.)
— Translation: The security of this system is extremely vulnerable, and immediate measures are necessary.

Understanding the kanji characters is key to mastering the word. The first kanji, 脆 (zei), means 'brittle' or 'fragile,' often used to describe things like dry leaves or thin ice. The second kanji, 弱 (jaku), is the standard character for 'weak.' Together, they create a picture of something that is not just lacking strength, but is prone to shattering or failing entirely under the slightest provocation.

地盤が脆弱な土地に家を建てるのは危険です。(Jiban ga zeijaku na tochi ni ie o tateru no wa kiken desu.)
— Translation: It is dangerous to build a house on ground with a weak foundation.

When you hear this word in the news, it's often in the context of 'vulnerable groups' (脆弱な立場の人々 - zeijaku na tachiba no hitobito). This refers to people who are socially or economically disadvantaged and are the first to suffer in times of crisis. The word elevates the discussion from a simple 'weakness' to a 'structural vulnerability' that requires systemic change.

Environmental Context: Ecosystems can be described as zeijaku if they are easily unbalanced by invasive species or climate change.

Using 脆弱 (zeijaku) correctly requires understanding its role as a na-adjective. This means you will typically see it in three forms: 脆弱な + [Noun], 脆弱だ/です at the end of a sentence, or 脆弱性 (zeijakusei) to turn it into a noun meaning 'vulnerability.'

Attributive Use (Modifying a Noun): You use zeijaku na to describe a specific thing.
Example: 脆弱な基盤 (zeijaku na kiban) - A fragile foundation.
Predicative Use (End of Sentence): You use zeijaku da to state a fact about a subject.
Example: この体制は脆弱だ。 (Kono taisei wa zeijaku da.) - This system/structure is fragile.

発展途上国は気候変動に対して非常に脆弱な立場にあります。(Hatten tojōkoku wa kikō hendō ni taishite hijyō ni zeijaku na tachiba ni arimasu.)
— Translation: Developing countries are in an extremely vulnerable position regarding climate change.

One of the most common ways you will see this word used in professional settings is as part of the compound 脆弱性 (zeijakusei). This is the standard term for security vulnerabilities in computer science. If you work in IT, you will hear about 'Vulnerability Assessment' (脆弱性診断 - zeijakusei shindan) or 'Vulnerability Management' (脆弱性管理 - zeijakusei kanri) almost daily.

最新のアプデを適用して、ソフトウェアの脆弱性を修正してください。(Saishin no apude o tekiyō shite, sofutowea no zeijakusei o shūsei shite kudasai.)
— Translation: Please apply the latest update to fix the software vulnerability.

When describing human psychology or health, zeijaku is less common than moroi (脆い - brittle/emotionally fragile) or yowai (弱い - weak). However, it can be used in medical or psychological contexts to describe a 'predisposition' or a 'vulnerability' to certain conditions. For example, seishin-teki zeijakusei (精神的脆弱性) refers to psychological vulnerability.

Comparison with 'Moroi': Moroi is often used for physical things that crumble easily (like cookies) or emotions (easily moved to tears). Zeijaku is more technical and implies a lack of resistance to external forces.

While 脆弱 (zeijaku) might not be a word you use when chatting with friends at a café, it is omnipresent in Japanese media, professional environments, and academic discourse. If you want to understand Japanese news or work in a corporate environment in Tokyo, this is a 'must-know' B2-level word.

1. The Evening News (NHK, etc.): News anchors use this word when discussing national security, disaster preparedness, or economic stability. For instance, 'Japan's energy self-sufficiency is zeijaku.'
2. Tech and Cybersecurity Blogs: Websites like ITmedia or Nikkei xTECH frequently report on zeijakusei (vulnerabilities) found in popular apps like LINE, Zoom, or Windows.
3. Academic Papers and Sociology: Scholars use the term to describe the fragility of social structures, especially when discussing the elderly or low-income families in the face of economic shifts.

日本は資源が乏しく、エネルギー供給体制が脆弱です。(Nihon wa shigen ga toboshiku, enerugī kyūkyū taisei ga zeijaku desu.)
— Translation: Japan is poor in resources, and its energy supply system is fragile.

In a professional setting, if a project manager says, '私たちの計画には脆弱な部分があります' (Watashitachi no keikaku ni wa zeijaku na bubun ga arimasu), they are signaling a serious concern. They aren't just saying the plan is 'weak'; they are saying it has a specific flaw that could lead to total failure if not addressed. This word choice demands attention and action.

高齢者は熱中症に対して非常に脆弱です。(Kōreisha wa netchūshō ni taishite hijyō ni zeijaku desu.)
— Translation: The elderly are extremely vulnerable to heatstroke.

Interestingly, the word is also appearing more in discussions about the 'Global Environment.' The 'fragility of the Earth' (地球の脆弱性 - chikyū no zeijakusei) is a common theme in environmental documentaries. It emphasizes that while the Earth seems vast and strong, its ecosystems are actually balanced on a very delicate and easily broken thread.

While 脆弱 (zeijaku) is a powerful word, it is easy to misuse if you treat it as a direct synonym for 'weak' (弱い - yowai). Here are the most common pitfalls English speakers and intermediate Japanese learners face.

Mistake 1: Using it for Physical Strength: You wouldn't say your muscles are zeijaku after a workout. For physical weakness, use 弱い (yowai) or 非力 (hiriki). Zeijaku is for structural or systemic weakness.
Mistake 2: Confusing it with 'Moroi': While they both mean 'fragile,' moroi (脆い) is used for things that crumble easily (like a cookie or a dry wall) or for people who cry easily (涙もろい - namida moroi). Zeijaku is more clinical and abstract.
Mistake 3: Over-formality: Using zeijaku in a casual conversation with friends about why you lost a video game will sound incredibly stiff or even sarcastic. Stick to yowai in casual settings.

❌ 腕の筋肉が脆弱です。(Ude no kinniku ga zeijaku desu.)
✅ 腕の筋肉が弱いです。(Ude no kinniku ga yowai desu.)
— Note: Muscles are 'yowai', not 'zeijaku'.

Another subtle mistake is using zeijaku to mean 'insufficient' or 'not enough.' While a 'vulnerable' system might be insufficient, the words are not interchangeable. For 'insufficient,' use fujūbun (不十分). Zeijaku specifically implies a point of failure that can be exploited.

❌ このお菓子は脆弱だ。(Kono okashi wa zeijaku da.)
✅ このお菓子は脆い。(Kono okashi wa moroi.)
— Note: Use 'moroi' for things that physically crumble or snap.

Finally, remember that zeijaku is a na-adjective, not a no-adjective. While some people might mistakenly say zeijaku no shisutemu, the grammatically correct form is zeijaku na shisutemu. However, the noun form zeijakusei does use no (e.g., shisutemu no zeijakusei).

To truly master 脆弱 (zeijaku), you should understand how it compares to other Japanese words for 'weakness' or 'fragility.' Choosing the right synonym depends on whether you are talking about health, personality, materials, or systems.

脆弱 (Zeijaku) vs. 弱い (Yowai): 弱い is the general term for 'weak.' It can be used for anything: weak tea, weak muscles, weak willpower. 脆弱 is formal and systemic. You use it for 'vulnerabilities' that lead to failure.
脆弱 (Zeijaku) vs. 脆い (Moroi): 脆い implies something that breaks or crumbles easily under pressure. It's often used for glass, cookies, or human emotions. 脆弱 is used more for systems, structures, and social positions.
脆弱 (Zeijaku) vs. 虚弱 (Kyojaku): 虚弱 is specifically used for physical health. A 'sickly child' is kyojaku-taishitsu (虚弱体質). You would not use zeijaku to describe a person's physical constitution.
脆弱 (Zeijaku) vs. 軟弱 (Nanjaku): 軟弱 often means 'weak-willed' or 'soft.' It can also describe 'soft ground' (軟弱地盤). While zeijaku ground is 'vulnerable' to sinking, nanjaku ground is just 'soft.'

彼は精神的に脆いところがあるが、組織の構造は脆弱ではない。(Kare wa seishin-teki ni moroi tokoro ga aru ga, soshiki no kōzō wa zeijaku de wa nai.)
— Translation: He has some emotional fragility, but the structure of the organization is not vulnerable.

In summary, choose zeijaku when you want to sound professional, analytical, or technical. Choose yowai for everyday life, moroi for things that break, and kyojaku for health. This distinction will make your Japanese sound much more natural and precise.

How Formal Is It?

Le savais-tu ?

The kanji 脆 (zei) is the same one used in the word for 'crispy' (saクサク) in some contexts, though usually written in kana. It literally describes the texture of something that snaps easily.

Guide de prononciation

UK zeɪdʒɑːku

US zeɪdʒɑːku

The pitch usually starts high on 'zei' and drops on 'jaku' (Atamadaka pattern) or stays flat (Heiban), depending on the dialect, but standard Tokyo is often flat.

Rime avec

Seijaku (Silence) Meijaku (Clarity - rare) Teijaku (Fixation) Keijaku (Lightness) Reijaku (Coolness) Heijaku (Equality/Calm) Kyōjaku (Strength and weakness) Kanjaku (Quietude)

Erreurs fréquentes

Pronouncing 'zei' as 'zee'. It must be 'zay'.
Mixing up 'jaku' with 'jyaku'. The 'j' is soft.
Stressing the 'ku' too much. The final vowel is often devoiced.
Forgetting the 'i' in 'zei'. It is a long vowel 'ze-e'.
Confusing it with 'seijaku' (silence).

Niveau de difficulté

Lecture 4/5

The kanji 脆 is rare and difficult to write, though easy to recognize in context.

Écriture 5/5

Writing 脆弱 from memory is a challenge even for some native speakers.

Expression orale 3/5

Pronunciation is straightforward, but finding the right context to use it is tricky.

Écoute 3/5

Common in news and technical reports, so it's easy to spot once you know it.

Quoi apprendre ensuite

Prérequis

弱い (Yowai) 強い (Tsuyoi) 安全 (Anzen) 危険 (Kiken) 守る (Mamoru)

Apprends ensuite

強靭 (Kyōjin) 堅牢 (Kenrō) 露呈 (Rosei) 克服 (Kokufuku) 基盤 (Kiban)

Avancé

脆弱性リサーチ (Vulnerability research) レジリエンス (Resilience) リスクマネジメント (Risk management)

Grammaire à connaître

Na-Adjective Modification

脆弱なシステム (Zeijaku na shisutemu)

Noun + 性 (Suffix for -ity/-ness)

脆弱性 (Zeijakusei - Vulnerability)

〜に対して (Towards/Against)

攻撃に対して脆弱だ。

〜が原因で (Because of...)

脆弱性が原因でトラブルが起きた。

〜を強いる (To force/impose)

脆弱な立場の人に犠牲を強いる。

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Exemples par niveau

このかべは脆弱です。

This wall is fragile/weak.

Simple [Noun] wa [Adjective] desu structure.

脆弱なはこを使わないでください。

Please do not use fragile boxes.

Using zeijaku na to modify a noun (hako).

そのおもちゃは脆弱だ。

That toy is fragile.

Informal 'da' ending.

脆弱なひもですね。

It's a weak string, isn't it?

Adding 'ne' for confirmation.

このつくえは脆弱ではありません。

This desk is not fragile.

Negative form 'dewa arimasen'.

脆弱な家はあぶないです。

Fragile houses are dangerous.

Zeijaku na + noun.

パスワードが脆弱です。

The password is weak.

Common modern context.

脆弱なところを直します。

I will fix the weak parts.

Zeijaku na + tokoro (place/part).

この古い橋は非常に脆弱です。

This old bridge is extremely fragile.

Adding 'hijyō ni' (extremely) for emphasis.

脆弱な地盤に建物を建ててはいけません。

You must not build buildings on weak ground.

Te-wa ikemasen (prohibition).

システムの脆弱性が見つかりました。

A vulnerability in the system was found.

Noun form 'zeijakusei'.

脆弱な立場の人を助けたいです。

I want to help people in vulnerable positions.

Zeijaku na tachiba (vulnerable position).

この紙袋は脆弱なので、重いものは入れないで。

This paper bag is fragile, so don't put heavy things in it.

Reason 'node' + request.

雨で地盤が脆弱になっています。

The ground is becoming weak due to the rain.

Ni natte imasu (state of becoming).

脆弱なセキュリティは問題です。

Weak security is a problem.

Na-adjective modifying 'sekyuriti'.

彼の理論は脆弱だと言われました。

It was said that his theory is weak.

Passive voice 'iwaremashita'.

このソフトウェアには重大な脆弱性があります。

This software has a serious vulnerability.

Jyuudai na (serious) + zeijakusei.

脆弱な経済基盤を強化する必要があります。

It is necessary to strengthen the fragile economic foundation.

Hitsuyō ga arimasu (necessity).

災害に対して脆弱な地域を調査しています。

We are investigating areas that are vulnerable to disasters.

Ni taishite (towards/against).

その組織の体制は驚くほど脆弱だった。

The structure of that organization was surprisingly fragile.

Odoro-ku hodo (to a surprising degree).

脆弱性を修正するためのパッチが配布された。

A patch to fix the vulnerability has been distributed.

Tame no (in order to).

食料供給の脆弱性が浮き彫りになった。

The vulnerability of the food supply was brought to light.

Ukibori ni naru (to be highlighted/exposed).

脆弱な心の持ち主は、ストレスに負けやすい。

People with fragile hearts/minds tend to succumb to stress.

Yasui (easy to/prone to).

この素材は熱に対して脆弱な性質を持っている。

This material has a property of being vulnerable to heat.

Seishitsu (property/nature).

サイバー攻撃により、インフラの脆弱性が露呈した。

A cyberattack exposed the vulnerabilities of the infrastructure.

Rosei suru (to be exposed/revealed).

脆弱な社会保障制度は、格差を広げる原因となる。

A fragile social security system becomes a cause for widening inequality.

Gen'in to naru (becomes a cause).

同社は脆弱性診断サービスを提供している。

The company provides vulnerability assessment services.

Zeijakusei shindan (vulnerability diagnosis).

心理的な脆弱性を抱える人々への支援が急務だ。

Support for people with psychological vulnerabilities is an urgent matter.

Kyūmu (urgent task).

脆弱なサプライチェーンを改善しなければならない。

We must improve the fragile supply chain.

Nakereba naranai (must).

このダムは構造的に脆弱であると指摘された。

It was pointed out that this dam is structurally fragile.

Shiteki sareru (to be pointed out).

脆弱な生態系を守るために、新しい法律が制定された。

A new law was enacted to protect fragile ecosystems.

Seitei sareru (to be enacted/established).

市場の脆弱性が原因で、株価が急落した。

Stock prices plummeted due to the vulnerability of the market.

Ga gen'in de (due to... as a cause).

近代文明の脆弱性は、皮肉にもその高度な複雑さに起因している。

The fragility of modern civilization ironically stems from its high level of complexity.

Kiin suru (to stem from/be caused by).

ゼロデイ脆弱性は、修正プログラムが存在しないため極めて危険だ。

Zero-day vulnerabilities are extremely dangerous because no fix program exists.

Zero-day (technical term).

脆弱な国家体制が、内戦の長期化を招いている。

The fragile state structure is leading to the prolongation of the civil war.

Maneku (to invite/lead to a bad result).

彼は自己の脆弱性を認めることで、真の強さを手に入れた。

By acknowledging his own vulnerability, he gained true strength.

Koto de (by means of).

グローバル経済の脆弱性を克服するための国際協力が不可欠である。

International cooperation is indispensable for overcoming the vulnerabilities of the global economy.

Fukakesu (indispensable).

その建築家は、脆弱な素材を用いて強固な空間を創り出した。

The architect used fragile materials to create a robust space.

Mochiite (using/utilizing).

情報の非対称性が、消費者にとっての脆弱性を生んでいる。

Information asymmetry creates vulnerability for consumers.

Hi-taishōsei (asymmetry).

脆弱な論理の上に築かれた議論は、すぐに破綻する。

An argument built on fragile logic will soon collapse.

Hatan suru (to collapse/go bankrupt).

人間存在の本質的な脆弱性を直視することは、実存主義の核心である。

Confronting the essential fragility of human existence is the core of existentialism.

Chokushi suru (to look squarely at).

その政策は、社会の最も脆弱な環（わ）を補強することに主眼を置いている。

The policy focuses primarily on reinforcing the weakest link in society.

Shugan o oku (to place the main focus).

アルゴリズムの脆弱性を突いた攻撃は、予測不可能な連鎖反応を引き起こした。

Attacks exploiting algorithmic vulnerabilities triggered unpredictable chain reactions.

Tsuita (having struck/exploited).

我々の文明がいかに脆弱な均衡の上に成り立っているかを痛感させられた。

We were made to feel deeply how our civilization is built upon such a fragile equilibrium.

Tsūkan saserareta (made to feel keenly).

脆弱性管理の不備が、企業の存続を揺るがす事態に発展した。

Inadequate vulnerability management evolved into a situation that shook the very survival of the company.

Sonzoku o yurugasu (to shake the existence/survival).

言語の持つ脆弱性が、誤解と対立の温床となっている側面は否定できない。

One cannot deny the aspect where the inherent fragility of language serves as a breeding ground for misunderstanding and conflict.

Onshō (breeding ground).

その論文は、現代金融システムの構造的脆弱性を鋭く批判している。

The paper sharply criticizes the structural vulnerabilities of the modern financial system.

Suruku hihan suru (to criticize sharply).

脆弱な美しさを湛えたその芸術作品は、観る者の心を打つ。

The work of art, filled with a fragile beauty, strikes the hearts of those who view it.

Tataeta (filled with/wearing - usually an expression).

Synonymes

弱い脆い虚弱な不安定な

Antonymes

強固な堅牢な

Collocations courantes

脆弱な地盤

脆弱な立場

脆弱な基盤

脆弱性を突く

脆弱性を修正する

精神的脆弱性

構造的脆弱性

脆弱な生態系

脆弱なリンク

脆弱な財務状況

Phrases Courantes

脆弱性が見つかる

— A vulnerability is found. Used when a security flaw is discovered in software.

新しい脆弱性が見つかりました。

脆弱性を抱える

— To have or carry a vulnerability. Used for systems or people with inherent weaknesses.

彼は精神的な脆弱性を抱えている。

脆弱な体制

— A fragile system or setup. Used when a group's organization is not strong.

脆弱な体制では危機に対応できない。

脆弱なインフラ

— Fragile infrastructure. Used for old bridges, roads, or power grids.

この国は脆弱なインフラが課題だ。

脆弱なバランス

— A fragile balance. Used for situations that could easily tip into disaster.

平和は脆弱なバランスの上に成り立っている。

脆弱な境界線

— A fragile boundary. Used metaphorically or physically.

生と死の脆弱な境界線。

脆弱な心の持ち主

— A person with a fragile heart. Used for someone easily hurt emotionally.

彼女は脆弱な心の持ち主だ。

脆弱な市場

— A fragile market. Used for financial markets that crash easily.

新興国の脆弱な市場。

脆弱な供給網

— Fragile supply network. Used for supply chains that break easily.

脆弱な供給網の改善。

脆弱な立場に置かれる

— To be placed in a vulnerable position. Used for social or professional status.

契約社員は脆弱な立場に置かれやすい。

Souvent confondu avec

脆弱 vs 静寂 (Seijaku)

Sounds similar but means 'silence' or 'quietude.' Don't confuse 'vulnerability' with 'peace and quiet'!

脆弱 vs 貧弱 (Hinjaku)

Means 'poor' or 'shabby.' While a 'hinjaku' system might be 'zeijaku,' 'hinjaku' focuses on the lack of resources/appearance.

脆弱 vs 軟弱 (Nanjaku)

Often used for 'soft/weak-willed' people or 'soft ground.' 'Zeijaku' is more about the risk of failure.

Expressions idiomatiques

"脆弱な環 (Zeijaku na wa)"

— The weakest link in a chain. The part of a system most likely to fail.

セキュリティの脆弱な環は人間である。

Formal

"脆弱な基盤の上に築く (Zeijaku na kiban no ue ni kizuku)"

— To build something on a shaky foundation. Implies future failure.

脆弱な基盤の上に築かれた平和。

Literary

"脆くも崩れ去る (Moroku mo kuzuresaru)"

— To crumble away all too easily. Often used when a dream or plan fails suddenly.

夢は脆くも崩れ去った。

Literary

"砂上の楼閣 (Sajō no rōkaku)"

— A castle on the sand. Something that looks impressive but has no foundation (related to zeijaku).

彼の計画は砂上の楼閣だ。

Idiomatic

"薄氷を踏む (Hakuhyō o fumu)"

— To tread on thin ice. Being in a fragile or dangerous situation.

薄氷を踏むような思いだ。

Idiomatic

"風前の灯火 (Fūzen no tomoshibi)"

— A candle in the wind. Being in an extremely fragile, precarious state.

彼の会社は風前の灯火だ。

Idiomatic

"豆腐の角に頭をぶつけて死ね (Tōfu no kado ni...)"

— Go bump your head on a corner of tofu and die. Used to mock someone extremely weak (slang/insult).

そんな脆弱なやつは豆腐の角に頭をぶつけて死ね！

Slang

"張子の虎 (Hariko no tora)"

— A paper tiger. Someone who looks strong but is actually weak/fragile.

彼は張子の虎だ。

Idiomatic

"独活の大木 (Udo no taiboku)"

— A giant wood-nettle. Someone large but useless/fragile.

体ばかり大きくて、独活の大木だ。

Idiomatic

"柳に風 (Yanagi ni kaze)"

— A willow in the wind. Being flexible and NOT fragile (the opposite concept).

柳に風と受け流す。

Idiomatic

Facile à confondre

脆弱 vs 弱い (Yowai)

Both mean 'weak.'

Yowai is general and subjective. Zeijaku is formal, technical, and implies a structural risk.

お酒に弱い (Weak to alcohol) vs セキュリティが脆弱 (Security is vulnerable).

脆弱 vs 脆い (Moroi)

Both mean 'fragile.'

Moroi is for things that physically crumble (cookies) or emotional sensitivity. Zeijaku is for systems and structures.

涙もろい (Easily moved to tears) vs 脆弱な地盤 (Vulnerable ground).

脆弱 vs 虚弱 (Kyojaku)

Both relate to weakness.

Kyojaku is strictly for physical health and body constitution. You can't have a 'kyojaku' computer system.

虚弱な子供 (A sickly child).

脆弱 vs 脆弱性 (Zeijakusei)

It's the noun form of the same word.

Zeijaku is the adjective (vulnerable); Zeijakusei is the noun (vulnerability).

脆弱な点 (Vulnerable point) vs 脆弱性がある (There is a vulnerability).

脆弱 vs 希薄 (Kihaku)

Both imply a lack of something.

Kihaku means 'thin' or 'diluted' (like air or interest). Zeijaku means 'structurally weak.'

関心が希薄だ (Interest is thin/low).

Structures de phrases

[Noun] は脆弱です。

この橋は脆弱です。

[Noun] の脆弱性を [Verb]。

システムの脆弱性を修正する。

[Noun] に対して非常に脆弱だ。

熱に対して非常に脆弱だ。

脆弱な [Noun] を強化する。

脆弱な基盤を強化する。

脆弱な立場に置かれる。

彼は脆弱な立場に置かれている。

構造的な脆弱性が露呈する。

構造的な脆弱性が露呈した。

[Concept] の脆弱性を突く。

論理の脆弱性を突く。

脆弱な均衡の上に成り立つ。

脆弱な均衡の上に成り立っている。

Famille de mots

Noms

脆弱性 (Zeijakusei) - Vulnerability

脆弱者 (Zeijakusha) - Vulnerable person

Verbes

脆弱化する (Zeijakuka suru) - To become fragile/vulnerable

Adjectifs

脆弱な (Zeijaku na) - Fragile/Vulnerable

Apparenté

脆い (Moroi)

弱い (Yowai)

脆弱性診断 (Zeijakusei shindan)

脆弱性対策 (Zeijakusei taisaku)

社会的脆弱性 (Shakai-teki zeijakusei)

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Comment l'utiliser

frequency

High in news, IT, and business; Low in daily casual conversation.

Erreurs courantes

腕が脆弱だ (Ude ga zeijaku da) → 腕が弱い (Ude ga yowai)
You don't use 'zeijaku' for physical muscle strength.
脆弱のシステム (Zeijaku no shisutemu) → 脆弱なシステム (Zeijaku na shisutemu)
Zeijaku is a na-adjective, not a no-adjective.
このクッキーは脆弱だ (Kono kukkī wa zeijaku da) → このクッキーは脆い (Kono kukkī wa moroi)
Use 'moroi' for things that physically crumble like food.
脆弱な天気 (Zeijaku na tenki) → 不安定な天気 (Fuantei na tenki)
'Zeijaku' isn't used for weather; 'fuantei' (unstable) is better.
脆弱な声 (Zeijaku na koe) → 弱々しい声 (Yowayowashii koe)
For a faint or weak voice, use 'yowayowashii'.

Astuces

IT Context

If you are in a meeting about software, use 'zeijakusei' to sound like an expert. It's the standard industry term.

Na-Adjective Rule

Don't forget the 'na' when modifying a noun! It's 'zeijaku na kiban', not 'zeijaku kiban'.

Nuance Check

Remember: Zeijaku = Systemic/Structural. Moroi = Physical/Emotional. Yowai = General.

Writing 脆

The kanji 脆 (zei) looks like 'danger' (危) inside a body (月). Fragility is a dangerous state for a body!

News Keywords

When you hear 'zeijaku', the next word is often 'taisaku' (countermeasure). They go together like 'problem' and 'solution'.

Business Tone

Using 'zeijaku' instead of 'yowai' instantly makes your Japanese sound more professional and high-level.

Compound Words

Look out for 'zeijakusei' in the terms of service or privacy policies of Japanese websites.

Z-Jack

Z-grade Jack (Zeijaku) is so weak he can't even pop out of his box without breaking.

Kyojaku vs Zeijaku

Kyojaku is for your grandma's health. Zeijaku is for the bank's firewall. Don't mix them up!

Disaster Prep

In Japan, 'zeijaku' is a serious word used in earthquake drills. It implies a need for urgent reinforcement.

Mémorise-le

Moyen mnémotechnique

Imagine a 'Zay' (Zei) ray gun hitting a 'Jack' (Jaku) in the box. The ray makes the Jack so brittle that he shatters. Zeijaku!

Association visuelle

Picture a glass bridge. It looks strong, but if one small crack appears, the whole thing is 'zeijaku' (vulnerable).

Word Web

Cybersecurity Foundation Economy Fragile Brittle Vulnerability Risk Structural

Défi

Try to find one 'vulnerability' (zeijakusei) in your daily routine today and describe it using the word.

Origine du mot

The word is a Sino-Japanese compound (kango). '脆' (zei) comes from the radical for 'flesh/body' and a phonetic component meaning 'to break.' '弱' (jaku) depicts two bent feathers, representing something that cannot stand straight.

Sens originel : Originally used to describe physical materials that were brittle or people who were sickly.

Sino-Japanese (Kanji-based).

Contexte culturel

When using 'zeijaku' to describe people or social groups, ensure you are using it in a systemic context (e.g., 'vulnerable to the economy') rather than sounding like you are insulting their personal strength.

In English, we often use 'vulnerable' for people's feelings. In Japanese, 'zeijaku' is more often for systems, though 'vulnerable groups' is a common translation.

Cybersecurity reports by IPA (Information-technology Promotion Agency, Japan). Sociological studies on 'The Fragile Middle Class' (脆弱な中間層). Disaster prevention manuals for 'Vulnerable People' (災害時脆弱者).

Pratique dans la vie réelle

Contextes réels

Cybersecurity

脆弱性を修正する
脆弱性を突く攻撃
最新の脆弱性情報
ゼロデイ脆弱性

Construction/Safety

脆弱な地盤
構造的な脆弱性
耐震性の脆弱さ
脆弱な壁

Economics

脆弱な経済基盤
市場の脆弱性
脆弱な通貨
供給網の脆弱性

Social Issues

脆弱な立場の人々
社会的脆弱性
脆弱な世帯
心理的脆弱性

Environment

脆弱な生態系
気候変動への脆弱性
環境の脆弱性
脆弱な自然

Amorces de conversation

"最近のサイバー攻撃ニュース、脆弱性が原因らしいですね。"

"このアプリのセキュリティ、脆弱なところはありませんか？"

"日本のエネルギー自給率は脆弱だと言われていますが、どう思いますか？"

"災害に備えて、地盤が脆弱な場所をチェックしておいたほうがいいですよ。"

"組織の脆弱性を克服するためには、何が必要だと思いますか？"

Sujets d'écriture

自分の生活の中で、一番「脆弱だ」と感じる部分はどこですか？（例：健康、貯金、スマートフォンのセキュリティなど）

社会の中で「脆弱な立場にある人々」を助けるために、何ができるか書いてみましょう。

「脆弱な美しさ」という言葉から、どんなものを想像しますか？

テクノロジーが進歩することで、私たちの生活はより「脆弱」になっていると思いますか？

過去に自分の「脆弱性」を克服した経験について書いてください。

Questions fréquentes

10 questions

Yes, but usually only in the phrase '脆弱な立場' (vulnerable position) or '精神的脆弱性' (psychological vulnerability). Using it to describe someone's physical strength sounds strange; use 'yowai' or 'kyojaku' instead.

Yes, especially in sci-fi or battle anime. A villain might mock a hero's '脆弱な防御' (vulnerable defense) or '脆弱な人間' (fragile humans). It sounds more menacing and intellectual than 'yowai'.

It is called 'ゼロデイ脆弱性' (Zero-dei zeijakusei). It refers to a security hole that is exploited before the developer has a chance to fix it.

It's 脆. The left side is the 'meat' radical (月), and the right side is 危 (danger) with a small extra stroke. Think: 'Meat in danger is fragile!'

Almost always negative. It indicates a flaw, a risk, or a lack of strength. However, in philosophy, acknowledging 'zeijaku' can be seen as a step toward true understanding.

Not really. For a weak signal, use 'shingō ga yowai' (信号が弱い). However, you could say the 'WiFi network's security' is 'zeijaku'.

Grammatically, 'zeijaku' is a na-adjective, so 'zeijaku na' is correct. 'Zeijaku no' is generally not used, though the noun 'zeijakusei no' (of the vulnerability) is common.

Yes, it is typically considered an N1 level word, though it appears in B2 level materials frequently due to its importance in modern society.

No. For food that is easily broken, use 'moroi' (脆い) or 'kuzure-yasui' (崩れやすい).

While there isn't one single word, 'kenrōsei' (堅牢性 - robustness) or 'kyōjinsei' (強靭性 - resilience) are commonly used as opposites in technical contexts.

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