このページをあなたの言語で

English

فارسی

العربية

Deutsch

Español

Français

한국어

Português

中文

हिन्दी

ホーム
学習
英語
語彙
bulletproof

B2 adjective #6,500 よく出る 10分で読める

bulletproof

上位6,500

練習する例文メモとヒント bulletproof 30秒で

解説 bulletproof in your Level:

At this beginner level, you might not use 'bulletproof' in your own speaking yet, but you can understand it as a very strong version of 'strong' or 'safe'. Think of a superhero who cannot be hurt by anything. In a simple sentence, you might see it used to describe a very strong car or a very safe house. It is a compound word made of 'bullet' (from a gun) and 'proof' (meaning protected from). So, 'bulletproof' means a gun cannot hurt it. It is like having a super shield. You can remember it by thinking of a thick wall that nothing can go through. Even at A1, it is good to know because it appears in many action movies and comic books.

無料登録して完全な解説を読む

At the A2 level, you can start to understand that 'bulletproof' isn't just for soldiers and police. People use it to talk about things that are very, very good and will not break. For example, 'This phone case is bulletproof' means the phone is very safe if you drop it. It is an adjective. You can use it to describe objects that are tough. You should also know that 'proof' is a suffix we use for other things like 'waterproof' (water cannot go in) or 'fireproof' (fire cannot burn it). 'Bulletproof' is the strongest of these words. It shows that something is made of very high-quality material that is difficult to damage.

無料登録して完全な解説を読む

As an intermediate learner, you should begin to recognize the figurative or metaphorical use of 'bulletproof'. It is often used in work or school to describe a plan or an idea that is perfect. If your teacher says your essay plan is bulletproof, they mean it is so well-organized that no one can find a mistake in it. You can use it when you are very confident about something. For example, 'I have a bulletproof way to remember new words.' This means your method always works and never fails. It is a great word to use instead of 'perfect' or 'very strong' because it sounds more professional and descriptive.

無料登録して完全な解説を読む

At the B2 level, you are expected to use 'bulletproof' accurately in professional and academic contexts. You should understand the nuance between 'bulletproof' and 'foolproof'. 'Bulletproof' implies that the thing can withstand an attack or criticism from the outside. You might talk about a 'bulletproof argument' in a debate or a 'bulletproof contract' in business. It suggests that you have done a lot of work to make sure there are no weaknesses. You should also be comfortable using it in the negative, such as 'No security system is 100% bulletproof,' to show a sophisticated understanding of risk and reality. It is a key word for expressing high levels of certainty and reliability.

At the C1 level, you should be able to use 'bulletproof' with stylistic flair. You can use it to describe complex systems, reputations, or philosophical positions. You might use it in a sentence like, 'The candidate's reputation was bulletproof until the scandal broke,' showing how the word describes a state of perceived invulnerability. You should also be aware of its synonyms like 'unassailable', 'ironclad', or 'irrefutable' and choose 'bulletproof' when you want to emphasize the 'protective' nature of the subject. You understand that in high-level business jargon, 'to bulletproof' is sometimes used as a verb meaning to stress-test or reinforce a proposal against all possible objections.

無料登録して完全な解説を読む

For a C2 learner, 'bulletproof' is a tool for precise communication. You recognize its idiomatic weight and can use it to create powerful imagery. You might use it to discuss the 'bulletproof nature of a mathematical proof' or the 'bulletproof logic of a legal precedent'. You are also sensitive to the potential for 'bulletproof' to be used ironically or hyperbolically. You can navigate the subtle differences between 'bulletproof', 'airtight', and 'watertight' with ease, selecting the one that best fits the specific 'threat' being resisted (physical force, logical leakage, or legal scrutiny). Your usage reflects a deep understanding of the word's history and its modern status as a hallmark of extreme durability and reliability.

無料登録して完全な解説を読む

練習する例文メモとヒント

bulletproof 30秒で

Literally means resisting bullets; figuratively means flawless, unassailable, and extremely reliable in any context.
Commonly used in law, business, and tech to describe plans, arguments, and systems that cannot fail.
A powerful adjective for B2+ learners to show high confidence and thorough preparation in professional speech.
Differentiated from 'foolproof' by its focus on resisting external attack rather than preventing human error.

The term bulletproof is a powerful compound adjective that bridges the gap between physical protection and abstract reliability. In its most literal sense, it describes materials—such as Kevlar vests, reinforced glass, or armored plating—specifically engineered to withstand the impact of ballistic projectiles. However, its metaphorical application is perhaps even more common in professional and academic discourse. When a person describes a plan, a legal contract, or a scientific theory as bulletproof, they are asserting that it is completely beyond reproach, immune to failure, and structurally sound against any form of scrutiny or opposition.

Literal Origin: The word originated in the mid-19th century to describe armor that could stop lead bullets. Today, it remains the standard term for protective gear used by law enforcement and military personnel.

In a figurative context, calling something bulletproof is a high compliment regarding its preparation and execution. For instance, a defense attorney might spend months building a bulletproof alibi for their client, meaning the evidence is so compelling and the timeline so tight that the prosecution cannot find a single gap to exploit. Similarly, in the world of software engineering, a bulletproof system is one designed with such high redundancy and error-handling that it is virtually impossible for it to crash, even under extreme load or unexpected input.

The CEO demanded a bulletproof strategy before presenting the merger to the board of directors.

Usage of this word is particularly high in competitive environments where stakes are significant. You will hear it in boardrooms, courtrooms, and laboratories. It conveys a sense of confidence and finality. If an argument is bulletproof, the debate is effectively over. It is not merely 'good' or 'strong'; it is unassailable. This nuance is critical for B2 learners to master: using 'bulletproof' suggests you have considered every possible counter-argument and neutralized it in advance.

Professional Context: In project management, a bulletproof timeline accounts for delays, budget shifts, and resource shortages, ensuring the project succeeds regardless of external pressures.

We need to ensure our data encryption is bulletproof to prevent any potential security breaches.

Social Context: Informally, one might say their friendship is bulletproof, meaning it has survived many hardships and cannot be easily broken by gossip or distance.

The athlete's training regimen was bulletproof, leading them to a gold medal without a single injury.

Using bulletproof correctly involves understanding its role as an adjective that can modify a wide variety of nouns, both concrete and abstract. It typically follows the verb 'to be' (predicative use) or precedes a noun (attributive use). When using it figuratively, it is essential to ensure the context implies a high level of scrutiny or a potential 'attack' that the subject is resisting.

Attributive Usage: Placement before the noun: 'The team developed a bulletproof methodology for the clinical trials.'

One of the most common grammatical patterns is the [Noun] + [is/seems/appears] + [bulletproof] structure. This is often used to express confidence in the stability of a situation. For example, 'The company's financial standing is bulletproof.' Here, the word acts as a strong descriptor of state. It can also be modified by adverbs of degree, though because bulletproof is an absolute adjective (something is either bulletproof or it isn't), adverbs like 'virtually' or 'nearly' are more common than 'very'.

Even though the plan seemed bulletproof, they still ran a final simulation to be sure.

Predicative Usage: Placement after the linking verb: 'After years of peer review, the scientist's findings were considered bulletproof.'

In professional writing, bulletproof is often paired with nouns like 'logic', 'evidence', 'defense', 'contract', and 'reputation'. These pairings emphasize that the item in question has been tested and has passed. For instance, 'a bulletproof reputation' suggests that even if someone tried to spread rumors, the person's character is so well-established that the rumors would not stick. In technical fields, it often modifies 'code' or 'security'.

The legal team worked overnight to ensure the contract was bulletproof before the signing ceremony.

She presented a bulletproof argument that left the opposition with no room for rebuttal.

Negative Usage: You can also use it in the negative to show vulnerability: 'No system is entirely bulletproof; there is always a risk of human error.'

Is the new software really bulletproof, or are we just hoping for the best?

The word bulletproof is ubiquitous in environments where reliability is the primary currency. In the high-stakes world of finance and investment banking, analysts often speak of 'bulletproof stocks' or 'bulletproof portfolios'. This refers to investments that are expected to remain stable or even thrive during economic downturns, much like a physical shield protects a soldier in battle. Hearing this word in a financial context signals a very low-risk, high-confidence asset.

Legal Dramas and Real Life: In legal settings, whether in a TV show like 'Suits' or in an actual courtroom, the term is used to describe evidence. A 'bulletproof witness' is someone whose testimony is so consistent and verified that cross-examination cannot shake them.

In the tech industry, specifically within cybersecurity and software development, 'bulletproof' is a standard term for code that has been rigorously tested through 'fuzzing' and 'penetration testing'. If a developer says their API is bulletproof, they are claiming it can handle malformed requests and malicious attacks without failing. However, seasoned engineers often use the term with a grain of salt, acknowledging that 'nothing is truly bulletproof'—a common idiom in the field that serves as a reminder to stay vigilant.

The detective knew that without a bulletproof case, the suspect would walk free on a technicality.

Journalism and politics are other areas where the word is frequently deployed. A politician might attempt to create a 'bulletproof policy'—one that is so popular or so logically sound that the opposing party cannot effectively criticize it without appearing unreasonable. Journalists, on the other hand, strive for 'bulletproof sourcing', ensuring that every fact in a major exposé is backed by multiple, reliable witnesses to avoid lawsuits or loss of credibility.

Sports Commentary: Commentators often describe a team's defense as bulletproof if they have not conceded any goals or points over several matches, implying a state of total dominance.

The startup's pitch was bulletproof, answering every potential investor's question before they even asked it.

Scientific Research: A 'bulletproof study' is one with a massive sample size and double-blind controls, making its conclusions nearly impossible to dispute in the scientific community.

The architect ensured the building's foundation was bulletproof against seismic activity.

One of the most frequent mistakes learners make with bulletproof is confusing it with its close relative, foolproof. While both words imply a high level of reliability, their 'targets' are different. Foolproof means something is designed so simply that even a 'fool' (someone making mistakes) cannot mess it up. Bulletproof, conversely, means something can withstand an external attack or intense scrutiny. You wouldn't say a microwave is 'bulletproof' to use; you would say it is 'foolproof'. You would say the microwave's warranty is 'bulletproof'.

Mistake 1: Confusing with Foolproof: Incorrect: 'This new coffee machine is bulletproof; anyone can use it.' Correct: 'This new coffee machine is foolproof; anyone can use it.'

Another error is using it as a verb. 'Bulletproof' is an adjective. You cannot 'bulletproof' your argument in the same way you can 'strengthen' it, although in very informal business jargon, people might say 'We need to bulletproof this plan.' While understandable, it is better to use 'make bulletproof' or 'reinforce' in formal writing. Additionally, learners sometimes try to use it for physical objects that aren't actually meant to resist bullets—for example, calling a very strong umbrella 'bulletproof' might be seen as a confusing hyperbole rather than a metaphor.

Don't say 'I need to bulletproof my car' unless you are literally adding armor to it.

Overuse is also a common pitfall. Because it is a strong, dramatic word, using it for every minor success can make your speech sound hyperbolic or 'salesy'. Reserve it for situations that truly involve defense against criticism or failure. For example, your morning routine isn't 'bulletproof'; it's just 'consistent'. However, your strategy for a multi-million dollar negotiation definitely should be 'bulletproof'.

Mistake 2: Degree Modifiers: Incorrect: 'His logic was very bulletproof.' Correct: 'His logic was absolutely bulletproof.'

A common error is misspelling it as two words: 'bullet proof'. In modern English, it is almost always written as one word: bulletproof.

Mistake 3: Misapplying to People: While you can have a 'bulletproof reputation', calling a person 'bulletproof' can be ambiguous. Does it mean they are physically tough, or emotionally distant? Context is king here.

Is his alibi bulletproof, or are there holes in his story?

While bulletproof is a fantastic word for high-stakes reliability, sometimes a different nuance is required. Understanding the synonyms and their specific contexts will help you sound more like a native speaker. The most common alternative in academic or technical writing is airtight. While bulletproof suggests resistance to external force, airtight suggests that nothing can 'leak' out—no logical gaps, no missing data.

Bulletproof vs. Airtight: 'Bulletproof' is used for defense against attack; 'airtight' is used for logical completeness. You have a bulletproof vest, but an airtight argument.

Another excellent alternative is robust. In engineering and economics, 'robust' describes a system that performs well under a variety of conditions. It is less dramatic than bulletproof but implies a similar level of strength. If you want to describe something that cannot be defeated or conquered, unassailable is the perfect high-level C1/C2 synonym. It is often used for reputations, positions, or leads in a race.

The champion held an unassailable lead as they entered the final lap of the race.

For physical objects, you might use indestructible or shatterproof. Shatterproof is specifically used for glass or plastic that doesn't break into sharp pieces. In a metaphorical sense, fail-safe is another great option, especially when describing a plan that has a backup in case the primary method fails. This is slightly different from bulletproof, which implies the primary method won't fail at all.

Comparison: Flawless: 'Flawless' refers to beauty or execution without errors, while 'bulletproof' refers to the strength and resilience of that execution.

The company's robust infrastructure allowed it to survive the global server outage.

Comparison: Water-tight: Similar to airtight, 'water-tight' is frequently used in British English to describe legal cases or alibis that have no flaws.

The evidence against the suspect was ironclad, leaving no room for doubt.

How Formal Is It?

豆知識

One of the first 'bulletproof' vests was made of silk and was developed in the late 1800s. It was surprisingly effective against low-velocity bullets but very expensive.

発音ガイド

UK /ˈbʊl.ɪt.pruːf/

US /ˈbʊl.ɪt.pruːf/

Primary stress is on the first syllable: BUL-let-proof.

韻が合う語

aloof goof spoof roof proof hoof waterproof fireproof

よくある間違い

Pronouncing 'bullet' like 'bulletin' (with an 'in' sound).
Putting the stress on 'proof' instead of 'bullet'.
Pronouncing 'proof' with a short 'u' sound like 'puff'.
Missing the 't' sound entirely between the two parts of the word.
Over-emphasizing the 't' in the middle, making it sound like two separate words.

難易度

読解 3/5

Easy to understand the literal meaning, but requires context for figurative use.

ライティング 4/5

Requires knowledge of common collocations like 'alibi' or 'strategy'.

スピーキング 4/5

A great word to use to sound more confident and professional.

リスニング 3/5

Clearly pronounced and often emphasized in speech.

次に学ぶべきこと

前提知識

bullet proof strong safe perfect

次に学ぶ

airtight unassailable robust resilient vulnerability

上級

impenetrable irrefutable indefatigable sturdy tenacious

知っておくべき文法

Compound Adjectives

The bulletproof vest (Noun + Adjective).

Absolute Adjectives

Something is bulletproof (no comparative 'more bulletproof').

Suffix -proof

Waterproof, fireproof, soundproof.

Predicative Adjectives

The plan is bulletproof (after the verb 'to be').

Attributive Adjectives

A bulletproof strategy (before the noun).

無料登録して完全な解説を読む

レベル別の例文

The police officer wears a bulletproof vest.

The police officer wears a vest that stops bullets.

Bulletproof is an adjective before the noun 'vest'.

Is this glass bulletproof?

Can bullets go through this glass?

Used as a predicate adjective after 'is'.

The superhero is bulletproof.

The superhero cannot be hurt by bullets.

Simple subject-verb-adjective structure.

The car has bulletproof windows.

The car windows are very strong.

Compound adjective modifying 'windows'.

They need bulletproof protection.

They need very strong safety.

Modifying the abstract noun 'protection'.

This metal is bulletproof.

This metal is very, very strong.

Direct description of a material.

A bulletproof jacket is heavy.

The special jacket is not light.

Adjective modifying the subject 'jacket'.

He felt bulletproof in his new suit.

He felt very safe and strong.

Metaphorical use at a basic level.

This phone case is almost bulletproof.

This case is very strong and protects the phone well.

Using 'almost' to modify the absolute adjective.

The bank uses bulletproof glass at the counters.

The glass at the bank is very safe.

Attributive use in a common setting.

Is your new plan bulletproof?

Is your plan perfect and safe from mistakes?

Figurative use for a 'plan'.

The soldiers have bulletproof helmets.

The helmets protect the soldiers' heads.

Plural noun modified by 'bulletproof'.

I want a bulletproof backpack for school.

I want a very strong backpack.

Expressing a desire for durability.

Nothing is completely bulletproof.

Everything can break sometimes.

Using 'completely' for emphasis.

The door is made of bulletproof steel.

The door is very strong metal.

Compound noun phrase 'bulletproof steel'.

That is a bulletproof argument!

That is a very good reason!

Exclamatory figurative use.

We need a bulletproof strategy to win the game.

We need a plan that cannot fail.

Applying the word to a competitive strategy.

Her alibi for the night of the crime was bulletproof.

Her story was perfect and had no holes.

Legal context: alibi.

The company's reputation for quality is bulletproof.

Everyone trusts the company completely.

Modifying 'reputation'.

He spent weeks making his presentation bulletproof.

He made sure his presentation had no errors.

Using 'making' + [object] + [adjective].

Is the security on this website bulletproof?

Is the website safe from hackers?

Context of digital security.

The new laws provide a bulletproof defense for consumers.

The laws protect people very well.

Abstract legal protection.

They thought their relationship was bulletproof until the move.

They thought their love was indestructible.

Emotional/relational context.

The athlete has a bulletproof mindset.

The athlete is mentally very strong.

Describing mental state.

The lawyer presented a bulletproof case to the jury.

The evidence was so strong it couldn't be argued against.

B2 level professional vocabulary.

Our backup system is bulletproof; we won't lose any data.

The system is extremely reliable.

Technical reliability.

You need to make sure your logic is bulletproof before you publish.

Your reasoning must be perfect.

Academic context: logic.

The merger was delayed until the contracts were bulletproof.

The contracts had to be legally perfect.

Corporate context.

Despite the criticism, her resolve remained bulletproof.

She did not let the criticism change her mind.

Describing internal strength/resolve.

Is there such a thing as a bulletproof investment?

Is any investment completely safe?

Financial context.

The software update includes a bulletproof fix for the bug.

The fix will definitely solve the problem.

Software development context.

She has a bulletproof excuse for being late.

Her reason is so good no one can be angry.

Common social usage.

The theory is elegant, but it is far from bulletproof.

The theory looks good but has many flaws.

Using 'far from' to negate the adjective.

The diplomat's immunity seemed bulletproof until the new treaty.

His protection was total until the rules changed.

Complex political context.

We must bulletproof our supply chain against future disruptions.

We must make our supply chain indestructible.

Informal use of 'bulletproof' as a verb in business.

The author's prose is bulletproof, leaving no room for ambiguity.

The writing is so clear it cannot be misunderstood.

Literary/stylistic context.

His reputation for integrity was considered bulletproof by his peers.

Everyone believed he was perfectly honest.

Passive construction with 'considered'.

The encryption algorithm is theoretically bulletproof.

In theory, the code cannot be broken.

Using 'theoretically' as a qualifier.

The project failed because the initial assumptions weren't bulletproof.

The starting ideas were wrong.

Causal relationship in a project setting.

She built a bulletproof career through hard work and networking.

Her career is very stable and successful.

Metaphor for career stability.

The witness's testimony provided the bulletproof evidence needed for a conviction.

The testimony was the final, perfect piece of the puzzle.

High-level legal precision.

To survive the audit, our financial records must be absolutely bulletproof.

The records must have zero errors.

Emphasis on absolute perfection.

The philosopher's ontological argument was initially thought to be bulletproof.

People thought the argument for existence was perfect.

Academic/Philosophical register.

A bulletproof methodology is the cornerstone of any credible scientific study.

A perfect way of doing research is essential.

Formal academic phrasing.

The fortress was designed to be bulletproof, yet it fell to internal treachery.

It was physically strong but failed because of a betrayal.

Contrast between physical and human failure.

Her defense of the policy was bulletproof, silencing even the harshest critics.

She spoke so well that no one could argue.

Describing rhetorical strength.

Is any digital infrastructure truly bulletproof in the age of quantum computing?

Can anything stay safe from new technology?

Rhetorical question in a high-tech context.

The team's synergy made their execution of the plan seemingly bulletproof.

They worked so well together that everything went perfectly.

Focus on 'synergy' and 'execution'.

類義語

impenetrable unassailable airtight flawless invincible robust

反対語

vulnerable flawed weak

よく使う組み合わせ

bulletproof vest

bulletproof glass

bulletproof plan

bulletproof argument

bulletproof alibi

bulletproof reputation

bulletproof contract

bulletproof logic

bulletproof security

bulletproof methodology

よく使うフレーズ

make something bulletproof

— To improve something until it has no flaws.

We need to make this proposal bulletproof before the meeting.

bulletproof your life

— To take steps to ensure you are safe from financial or personal failure.

Saving money is one way to bulletproof your life against emergencies.

practically bulletproof

— Almost impossible to defeat or break.

This new encryption is practically bulletproof.

bulletproof coffee

— A specific type of high-fat coffee drink (brand name/trend).

He starts every morning with a cup of bulletproof coffee.

bulletproof casing

— A hard outer shell that protects internal components.

The black box is housed in a bulletproof casing.

bulletproof defense

— A strategy or physical barrier that cannot be breached.

The team's bulletproof defense led them to the finals.

bulletproof reasoning

— Thinking that is completely logical and sound.

Her bulletproof reasoning made the decision easy for everyone.

bulletproof evidence

— Proof that is so strong it cannot be denied.

The DNA results provided bulletproof evidence of his innocence.

bulletproof clothing

— Garments made with protective materials.

Some high-profile CEOs wear bulletproof clothing in public.

bulletproof smile

— A confident or fixed expression that hides true emotions (literary).

She wore a bulletproof smile to hide her nervousness.

よく混同される語

bulletproof vs foolproof

Foolproof means easy to use; bulletproof means resistant to attack.

bulletproof vs waterproof

Waterproof is only for liquids; bulletproof is for force/logic.

bulletproof vs fireproof

Fireproof is only for heat; bulletproof is for physical impact.

慣用句と表現

"Nothing is bulletproof"

— A reminder that even the best plans or systems can fail.

We have double-checked everything, but remember, nothing is bulletproof.

Neutral

"Bulletproof as a tank"

— Extremely strong and durable.

This old truck is as bulletproof as a tank.

Informal

"Ironclad and bulletproof"

— A double emphasis on something being impossible to break or change.

The legal team made the agreement ironclad and bulletproof.

Formal

"A bulletproof soul"

— Someone who is emotionally resilient and cannot be hurt by words.

After all she's been through, she has a bulletproof soul.

Literary

"Bulletproof the budget"

— To add extra funds to a budget to cover any possible cost increases.

We need to bulletproof the budget to account for inflation.

Business

"Through a bulletproof lens"

— Seeing the world in a way that is overly protected or cynical.

He views every business deal through a bulletproof lens.

Literary

"Bulletproof your resume"

— To add skills and experiences that make you an irresistible candidate.

Learning a second language is a great way to bulletproof your resume.

Professional

"Bite the bullet"

— Related idiom: To endure a painful situation with courage.

I had to bite the bullet and tell the boss about the mistake.

Neutral

"Silver bullet"

— Related idiom: A simple and magical solution to a complicated problem.

There is no silver bullet for the climate crisis.

Neutral

"Sweat bullets"

— Related idiom: To be extremely nervous or worried.

He was sweating bullets during the final exam.

Informal

間違えやすい

bulletproof vs Foolproof

Both mean 'cannot fail'.

Foolproof focuses on preventing human error (even a 'fool' can do it). Bulletproof focuses on resisting external pressure or criticism.

The instructions are foolproof; the security is bulletproof.

bulletproof vs Airtight

Both describe perfect logic.

Airtight suggests no 'leaks' or missing pieces. Bulletproof suggests it can survive being 'shot at' (criticized).

His logic was airtight; his defense was bulletproof.

bulletproof vs Shatterproof

Both are about glass.

Shatterproof glass breaks safely; bulletproof glass stops the bullet entirely.

The phone has a shatterproof screen, but it's not bulletproof.

bulletproof vs Robust

Both mean strong.

Robust is a general term for health and strength. Bulletproof is more extreme and specific to defense.

The economy is robust, but the banking laws aren't bulletproof.

bulletproof vs Ironclad

Both mean unbreakable.

Ironclad is most often used for rules, contracts, and laws. Bulletproof is used for plans and physical protection.

The company has an ironclad policy against bribery.

文型パターン

The [Noun] is bulletproof.

The car is bulletproof.

It has [Adjective] [Noun].

It has bulletproof glass.

I have a bulletproof [Noun].

I have a bulletproof plan.

The [Noun] seems bulletproof.

The argument seems bulletproof.

To make [Noun] bulletproof, we must...

To make the system bulletproof, we must add more servers.

Despite being [Adjective], it isn't bulletproof.

Despite being strong, it isn't bulletproof.

The bulletproof nature of [Noun] is...

The bulletproof nature of his logic is impressive.

Rendered [Noun] bulletproof by [Action].

The contract was rendered bulletproof by the new clause.

語族

名詞

bulletproofness (rarely used)

bullet (root)

proof (root)

動詞

bulletproof (informal business use)

形容詞

bulletproof

使い方

frequency

Common in professional and media English.

よくある間違い

Using 'bulletproof' when you mean 'easy'. → The exam was foolproof.
If the exam was easy to understand, use 'foolproof'. If the exam's security was impossible to break, use 'bulletproof'.
Writing 'bullet proof' as two words. → The glass is bulletproof.
Modern English usage requires the word to be closed (one word) when used as an adjective.
Saying 'more bulletproof'. → The plan is more robust.
Because bulletproof is absolute, 'more' is logically incorrect. Use 'more robust' or 'closer to being bulletproof'.
Using it to describe a person's health. → He has a strong constitution.
While 'bulletproof' can describe a reputation, using it for health is non-standard. Use 'robust' or 'resilient' instead.
Confusing 'bulletproof' with 'fireproof'. → The safe is fireproof.
Make sure you are describing the correct type of protection. Bulletproof specifically relates to kinetic force/impact.

ヒント

Choose your noun wisely

Bulletproof works best with nouns that imply a struggle or potential failure. Use it for 'strategies' and 'defenses' rather than 'sandwiches' or 'walks'.

Avoid over-hyping

If you call every small idea 'bulletproof', people might stop believing you. Save it for the big, important things that you have truly perfected.

No 'very'

Since bulletproof is an absolute, try using 'absolutely' or 'completely' instead of 'very'. It sounds much more natural to native ears.

Business English

In a job interview, saying you have a 'bulletproof work ethic' is a very strong way to show you are reliable and hardworking.

Suffix practice

Learn other '-proof' words like 'childproof' or 'foolproof' to expand your vocabulary quickly using the same logic.

Watch the 'T'

In the middle of 'bulletproof', the 't' is often a 'stop t'. Don't let it disappear, but don't make it too loud either.

Legal precision

In legal writing, use 'bulletproof' to describe evidence that is corroborated by multiple sources.

Catch the metaphor

When you hear it in a movie, ask yourself: are they talking about a real vest, or is the character just feeling very confident?

Check the room

In very casual settings, 'bulletproof' might sound a bit intense. 'Solid' or 'great' might be better for low-stakes conversations.

Visual cue

Associate the word with the image of a 'Vault'. A vault is designed to be bulletproof to protect the gold inside.

暗記しよう

記憶術

Think of a 'Bullet' hitting a 'Proof' (a printed copy of a book). If the 'Proof' is so thick the 'Bullet' stops, it is 'Bulletproof'.

視覚的連想

Imagine a shield made of solid steel that has a 'check mark' on it, signifying it has been tested and passed.

Word Web

Shield Safety Logic Armor Success Reliable Strong Unbreakable

チャレンジ

Try to use 'bulletproof' in three different ways today: once about an object, once about a plan, and once about a reason.

語源

Formed in the mid-19th century (around 1840-1850) from the noun 'bullet' and the adjective 'proof'. The concept of 'proof' against something (meaning tested and resistant) dates back to the 16th century in words like 'fireproof'.

元の意味： Specifically referring to armor or clothing that could stop the lead balls fired from muskets or early rifles.

Germanic (English)

文化的な背景

Be mindful when using this word in regions currently affected by gun violence; the figurative use is fine, but the literal context can be sensitive.

Commonly used in 'Silicon Valley' tech culture to describe high-availability systems.

The song 'Bulletproof' by La Roux (2009) about emotional protection. The movie 'Bulletproof' (1996) starring Adam Sandler and Damon Wayans. The 'Bulletproof Diet' by Dave Asprey, which popularized 'bulletproof coffee'.

実生活で練習する

実際の使用場面

Business Planning

bulletproof strategy
bulletproof ROI
bulletproof timeline
bulletproof budget

Legal Defense

bulletproof alibi
bulletproof witness
bulletproof evidence
bulletproof contract

Cybersecurity

bulletproof encryption
bulletproof firewall
bulletproof hosting
bulletproof code

Manufacturing

bulletproof glass
bulletproof material
bulletproof design
bulletproof testing

Personal Growth

bulletproof mindset
bulletproof routine
bulletproof confidence
bulletproof resolve

会話のきっかけ

"Do you think it's possible for any business plan to be truly bulletproof?"

"What kind of evidence would you consider bulletproof in a court of law?"

"How can a person build a bulletproof reputation in their chosen career?"

"If you could make one object you own bulletproof, what would it be?"

"Have you ever had a plan that you thought was bulletproof but it failed?"

日記のテーマ

Describe a time when you had a bulletproof argument. How did the other person react?

What steps can you take to make your current study routine more bulletproof?

Write about a fictional character who is physically bulletproof. What are their weaknesses?

In your opinion, is 'bulletproof' security a reality or an illusion in the digital age?

Reflect on a relationship in your life that you consider bulletproof. Why is it so strong?

よくある質問

10 問

Yes, but usually metaphorically. It means they are emotionally tough or their reputation is so good they cannot be hurt by rumors. For example, 'As a politician, he seems bulletproof.' This implies scandals don't affect him.

In modern English, it is almost always written as one word: 'bulletproof'. While you might see 'bullet-proof' with a hyphen in older texts, the single-word version is standard now.

Technically, very few things are 100% 'bulletproof' (nothing can stop every type of bullet). In engineering, 'bullet-resistant' is the more accurate term. However, in common English, 'bulletproof' is the word everyone uses.

It is neutral to formal. It is perfectly acceptable in business meetings, legal contexts, and academic writing, though it has a slightly dramatic tone.

In informal business jargon, yes. People say 'We need to bulletproof this proposal.' This means to check it for every possible error. However, this is not standard formal English.

Vests, glass, cars, plans, alibis, logic, contracts, and reputations are the most common nouns paired with this adjective.

Strictly speaking, no. It is an absolute. However, people often use 'more' or 'most' informally, or 'virtually' and 'nearly' formally to show how close something is to being perfect.

Yes, it is very common in tech to describe code that doesn't crash or security that can't be hacked.

The noun form is 'bulletproofness', but it is very rare. Usually, people use phrases like 'the reliability of...' or 'the strength of...' instead.

It's a brand name. The creator used the word to imply that the drink makes you feel 'invincible' or 'extremely high-performing' throughout the day.

無料登録してヒントとメモを見る