Translation guide
The English verb "warn" covers a range of situations from giving a serious caution about danger to giving a mild heads-up. Japanese uses different verbs and expressions depending on the severity, formality, and whether you are warning against an action or informing about a fact.
To caution someone strongly about a real danger, risk, or serious negative outcome.
The most direct equivalent for a formal or serious warning. Often used in official contexts, signs, or when there is a clear danger.
彼は危険について警告した。
He warned about the danger.
The doctor warned of the dangers of smoking.
To warn or caution, often used in everyday situations. It can also mean 'to be careful' or 'to pay attention'. Softer than 警告する.
母は私に車に注意するように言った。
My mother warned me to watch out for cars.
先生は遅刻しないように注意した。
The teacher warned us not to be late.
To admonish or warn, often with a moral or disciplinary tone. Used in formal or literary contexts.
彼は怠惰を戒めた。
He warned against laziness.
To tell someone not to do something because it is risky or will have bad consequences.
A common pattern meaning 'to tell someone not to do something'. The verb before ない is in plain negative form.
彼は私に触らないように言った。
He warned me not to touch it.
警察は夜遅く出歩かないように警告した。
The police warned people not to walk around late at night.
A more direct and casual way to say 'don't do ~'. Often used in informal speech.
彼は行くなと言った。
He told me not to go. (He warned me not to go.)
To inform someone about something (often negative or inconvenient) before it happens, so they can prepare.
To give advance notice, often used for warnings about future events or changes.
会社は人員削減を予告した。
The company warned of job cuts.
A casual phrase meaning 'to tell in advance' or 'to warn beforehand'. Often used among friends or in informal settings.
あらかじめ言っておくけど、明日は雨だよ。
Just to warn you, it's going to rain tomorrow.
To issue a warning or alert, often used in official announcements or public service messages.
政府は熱中症に注意喚起した。
The government warned about heatstroke.
To tell someone that there will be negative consequences if they do or don't do something.
A common conditional warning pattern. 'If you don't do ~, ~ will happen.' The tone can be serious or light depending on context.
早くしないと遅刻するよ。
I'm warning you, if you don't hurry up, you'll be late.
宿題をしないとゲームは禁止だよ。
I warn you, if you don't do your homework, no video games.
Literally 'I'll warn you (in advance)'. Used to issue a direct warning or threat.
警告しておく。次やったら許さない。
I'm warning you. If you do it again, I won't forgive you.
警告する (keikoku suru) is stronger and more formal, often used for serious dangers or official warnings. 注意する (chūi suru) is more common in daily life and can simply mean 'to be careful' or 'to caution' without a strong sense of alarm.
津波警報が警告された。
A tsunami warning was issued.
母は私に階段に注意するように言った。
My mother warned me to be careful on the stairs.
In casual conversation, using 警告する can sound overly dramatic or stiff. For everyday warnings, use 注意する or a pattern like 〜ないように言う.
友達に「遅れるよ」と注意した。
I warned my friend, 'You'll be late.'
彼女は上司の機嫌が悪いと教えてくれた。
She warned me that the boss was in a bad mood.
Here 'warned' is more like 'gave a heads-up', so 教えてくれた (informed me) is natural.