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N4Lesson notes · Oct 4, 2026

Dangerous in Japanese: 危あぶない (あぶない) vs 危険きけん (きけん), and the shout "Look out!

"Dangerous" in Japanese is 危あぶない (あぶない) in everyday speech and 危険きけん (きけん) in signs, news, and formal writing — and 危あぶない! shouted on its own means "Look out!"

If you search "dangerous in Japanese", you will find two words that look like the same answer. They are not interchangeable. One is what a person says when a cup is about to fall off the table. The other is what a sign says at the edge of a cliff. Picking the wrong one will not break the conversation, but it will make you sound like a warning label or like someone shouting at a sign.

This post covers both words, the shout, the "that was close" form, how やばい fits in, and the line between 危あぶない (dangerous) and 怖こわい (scary).

The basics

What is "dangerous" in Japanese?

The everyday word is 危あぶない (あぶない), an い-adjective meaning "dangerous," "risky," or "unsafe." It describes a thing, a place, or a situation that could hurt someone.

この道みちは危あぶないですよ。 — This road is dangerous. (polite, friendly warning) 夜よる、一人ひとりで歩あるくのは危あぶない。 — Walking alone at night is dangerous. (casual, giving advice)

Because it is an い-adjective, it behaves like any other: 危あぶなくない (not dangerous), 危あぶなかった (was dangerous), 危あぶなくて (dangerous and...). If you want a refresher on how those endings work, see い-adjectives vs な-adjectives.

What does 危あぶない! mean when someone shouts it?

Shouted alone, 危あぶない! means "Look out!" or "Watch out!" — a warning that something bad is about to happen right now. It is one of the first words a Japanese speaker blurts out before they have time to think.

危あぶない! — Look out! (shouted, an instant warning) 危あぶない、下さがって! — Watch out, step back! (urgent, addressing someone close)

Notice that the shout and the adjective are the same word. The difference is purely timing and tone: a short sharp 危あぶない! is a reaction, and 危あぶないですよ is a calm heads-up.

What is 危険きけん (きけん)?

危険きけん is a noun meaning "danger" and a な-adjective meaning "dangerous," and it belongs to written, official, and serious spoken language. You see it on warning signs, in news reports, and in manuals.

危険きけん! 近ちかづかないでください。 — Danger! Please do not come close. (written, on a sign) この川かわは増水ぞうすいすると危険きけんです。 — This river is dangerous when the water rises. (polite, informative, the way an announcement would phrase it) 危険きけんな場所ばしょには入はいらないでください。 — Please do not enter dangerous places. (formal, a rule)

Because 危険きけん is a な-adjective, it connects to a noun with な: 危険きけんな場所ばしょ, 危険きけんな人ひと. 危あぶない connects directly: 危あぶない場所ばしょ, 危あぶない人ひと. Same meaning, different grammar.

危あぶない vs 危険きけん: which one do you use?

Use 危あぶない when you are talking to someone in the moment, and 危険きけん when you are writing, announcing, or being official. That is the whole contrast.

危あぶない 危険きけん
Part of speech い-adjective Noun / な-adjective
Feels like Spoken, immediate, personal Written, official, serious
Typical place Conversation, shouts, warnings between people Signs, news, manuals, rules
Shout alone? Yes: 危あぶない! Rare; sounds like a sign being read aloud
Example 危あぶないよ。 危険きけんです。

You can say 危険きけん out loud, and people do, but it sounds heavier. Telling a friend "危険きけんだよ" when they reach for a hot pan makes them wonder what is going on. 危あぶないよ is what they expect.

Beyond the basics

How do you say "that was close"?

危あぶなかった means "that was close" or "that was dangerous (and I just avoided it)." It is the past tense of 危あぶない, used after the danger has passed.

危あぶなかった! ぶつかるところだった。 — That was close! I almost hit it. (casual, relieved) 危あぶなかったですね。 気きをつけてください。 — That was a close one. Please be careful. (polite, to a stranger or coworker)

English has "phew" and "that was close." Japanese often uses 危あぶなかった for both, with a breath out. It is not describing the place as dangerous, it is describing the moment you just escaped.

What about 危あぶなっかしい?

危あぶなっかしい describes a person or action that looks likely to go wrong, like someone carrying too many cups. It is less about real danger and more about watching someone and feeling nervous.

あの子こ、歩き方あるきかたが危あぶなっかしいね。 — The way that kid walks makes me nervous. (casual, an observation)

It is a mild, half-affectionate word. You would not use it on a sign.

Is やばい the same as 危あぶない?

やばい is slang that can mean "dangerous" or "this is bad," but it also means "amazing," so the situation decides. The danger meaning is older. Today the same word can cover disaster, surprise, and delight.

やばい、遅刻ちこくする! — Uh-oh, I'm going to be late! (casual, panic) この道みち、暗くらくてやばいよ。 — This road is dark and kind of sketchy. (casual, a friend's warning)

For the full range of やばい, including the positive sense, read our guide to やばい. To see how its positive side overlaps with another word, see amazing in Japanese: すごい.

The rule of thumb: やばい with a worried face is "bad," and やばい with a big smile is "wow." 危あぶない has no positive side at all.

What do the warning signs say?

Signs use a small set of stock words: 危険きけん, 注意ちゅうい, and 立入禁止たちいりきんし. Each one asks for a different level of caution.

注意ちゅうい — Caution. (a general warning, milder than 危険きけん) 立入禁止たちいりきんし — No entry. (literally "entering is forbidden," on fences and doors) 足元あしもとに注意ちゅういしてください。 — Please watch your step. (polite, station announcement)

注意ちゅうい is a noun meaning "attention" or "caution," and 注意ちゅういしてください is the standard polite warning form. 立入禁止たちいりきんし (たちいりきんし) is a rule, not a description: it does not say the area is dangerous, only that you may not go in.

How do you tell someone to be careful?

気きをつけて (きをつけて) means "be careful" and is the friendly, everyday way to warn or send someone off. It is softer than 危あぶない and used before danger arrives.

気きをつけてね。 — Take care. (casual, to a friend leaving) 足元あしもと、気きをつけて。 — Watch your step. (casual, at a staircase)

You can use 気きをつけて as a farewell, which is a whole different job from 危あぶない! For that sense, see 気きをつけて: take care in Japanese.

危あぶない vs 怖こわい: what's the difference?

危あぶない describes something that can actually hurt you, while 怖こわい (こわい) describes how you feel, or how something makes you feel. A thing can be 怖こわい without being 危あぶない, and the other way around.

あの犬いぬは危あぶないよ。 — That dog is dangerous. (a fact: it might bite) 私わたしはあの犬いぬが怖こわい。 — I am scared of that dog. (a feeling: it scares me) お化ばけ屋敷やしきは怖こわいけど、危あぶなくない。 — The haunted house is scary, but it isn't dangerous. (casual, both words in one sentence)

A cliff edge is 危あぶない. A ghost story is 怖こわい. A fast driver is both. For the feeling side in depth, read scary in Japanese: 怖こわい.

How does it sound in anime?

In anime, 危あぶない! is the cry right before an attack lands, and the next frame is usually a character pushing someone out of the way. It is short on purpose: there is no time for a longer sentence.

危あぶない! よけて! — Look out! Dodge! (shouted, in a fight) 危あぶないところだった…。 — That was a close call... (quiet, after the enemy's attack misses) あんな無茶むちゃをして、危あぶないだろ! — That was a reckless thing to do. It's dangerous, you know! (angry, a worried friend scolding)

The last line shows the other face of the word. 危あぶない can express worry as anger: the person is not mad at you, they are scared of what almost happened.

Common mistakes

  • Shouting 危険きけん! to warn a friend. It sounds like a sign. In the moment, use 危あぶない!
  • Using 危あぶない where an official sign wants 危険きけん. Warning signs and manuals usually say 危険きけん or 注意ちゅうい; 危あぶない is more at home in speech and in friendly notices (危あぶないですから…).
  • Using 危険きけん with no な before a noun. The pattern is 危険きけんな場所ばしょ, not 危険きけん場所ばしょ.
  • Treating 危あぶない and 怖こわい as the same. 危あぶない is about the situation. 怖こわい is about the feeling. "I'm scared" is 怖こわい, not 危あぶない.
  • Assuming やばい is always bad. Check the face and the tone. It can be a compliment.

Practice

Build each answer before opening it. Questions 1 and 2 are a pair on the key contrast, and so are questions 6 and 7.

1. A friend is about to touch a hot pan. What do you say?

Show answer

危あぶない! — an immediate spoken warning. 危険きけん would sound like a sign being read aloud.

2. You are writing a sign for a cliff edge. Which word fits: 危あぶない or 危険きけん?

Show answer

危険きけん — written, official, and serious. 危あぶない is for speech.

3. Is 危険きけん an い-adjective or a な-adjective? How do you say "dangerous place"?

Show answer

な-adjective — 危険きけんな場所ばしょ — な links it to the noun. The い-adjective 危あぶない links directly: 危あぶない場所ばしょ.

4. A car passes very close to you and you avoid it. What do you say after?

Show answer

危あぶなかった — the past tense, used after the danger has passed: "that was close."

5. What does 立入禁止たちいりきんし tell you?

Show answer

No entry — it states a rule, not a description. The area might be dangerous, but the sign only forbids going in.

6. A haunted house makes you nervous, but nobody can be hurt. Which word describes it: 怖こわい or 危あぶない?

Show answer

怖こわい — it describes the feeling. Nothing here can actually hurt you.

7. A dog might bite a child. Which word describes the situation: 怖こわい or 危あぶない?

Show answer

危あぶない — it describes a real risk. 怖こわい would only describe how someone feels about the dog.

8. Your friend says この道みち、暗くらくてやばいよ。 What does やばい mean here?

Show answer

Sketchy or unsafe — やばい is a casual way to warn about danger. Context and tone tell you it is not the "amazing" meaning.

9. What is the difference between 危あぶない! and 気きをつけて?

Show answer

危あぶない! warns about danger right now; 気きをつけて asks someone to be careful in general. 気きをつけて also works as a friendly goodbye.

10. Someone watches a child carry too many cups. Which word fits the nervous feeling?

Show answer

危あぶなっかしい — it describes an action that looks likely to go wrong, more about the watcher's unease than real danger.

In a 30-minute trial lesson, shout 危あぶない! in a street scene and read out 危険きけんです as if from a warning sign, and hear the difference.

FAQ

Is 危あぶない or 危険きけん more common? In conversation, 危あぶない is far more common. 危険きけん appears mostly in writing, signs, and announcements. You will hear both, but in different places.

Can you say 危険きけん out loud? Yes, but it sounds serious and formal. 危険きけんです is fine in a warning like a station announcement. Between friends, 危あぶないよ is the natural word.

How do I say "That's dangerous!" politely? Use 危あぶないですよ。 The よ makes it a friendly warning. For a very formal or written style, use 危険きけんです。

Does 危あぶない always mean physical danger? No. It can describe risky ideas, shaky plans, or an unreliable person too. 危あぶない橋はしを渡わたる (to take a risky route) means to do something with serious risk, and 危あぶない人ひと can mean someone who seems unsafe to be around.

Is やばい a good or bad word? Both. It can mean "dangerous," "terrible," or "amazing." Tone and context decide, so listen to the voice and the face before you answer.

What is the difference between 危あぶない and 気きをつけて? 危あぶない says something is dangerous. 気きをつけて asks someone to be careful. The first is a description or a shout, the second is a request or a goodbye.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab — the first column becomes the front, the second the back.

危ない	あぶない — dangerous, look out!
危険	きけん — danger, dangerous (formal)
危なかった	あぶなかった — that was close
危なっかしい	あぶなっかしい — shaky, makes you nervous
やばい	やばい — bad, dangerous, amazing (slang)
注意	ちゅうい — caution, attention
立入禁止	たちいりきんし — no entry
気をつけて	きをつけて — be careful, take care
怖い	こわい — scary, afraid
場所	ばしょ — place
道	みち — road, way
夜	よる — night, evening

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime, so most of the example sentences on this blog come from lines I've actually heard students ask about — including this one, which comes up whenever a learner first meets a warning sign. For practice with feedback, Book a trial lesson · $13, or work through Japanese practice exercises first.

Sources: the author's own lessons and standard reference grammars.

More drills like the ones above, plus a timed JLPT-style mock test: Practice · N4 · Read something at this level: JLPT N4 stories with audio

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