Translation guide
Describes something extremely unusual, unprecedented, or shocking. In Japanese, this is expressed through adjectives, set phrases, or emphatic negation patterns.
To say that something is so rare or new that it has never been known before.
To express that something is so bad or unacceptable that it is beyond normal experience.
To say that someone or something is not widely recognized or has no reputation.
Means 'unknown' or 'obscure'. Used for people, places, or things that are not famous.
彼はまだ無名の歌手だ。
He is still an unheard-of singer.
Directly translating 'unheard-of' as 聞かれていない (kikarete inai) is unnatural. Use the expressions above instead.
前代未聞 is more colloquial and can be used for any surprising event. 未曾有 is heavier, often reserved for large-scale disasters or historical crises, and appears more in news reports.
A common, emphatic word meaning 'unprecedented' or 'unheard-of in history'. Used for shocking events or situations.
そんな前代未聞の事件は初めてだ。
That kind of unheard-of incident is a first.
Literally 'I have never heard of it'. A natural, everyday way to express that something is unheard-of.
そんな話は聞いたことがない。
I've never heard of such a thing.
Means 'unprecedented' or 'record-breaking', often used for disasters or crises. More formal and written.
未曾有の大災害が起きた。
An unheard-of catastrophe occurred.
Means 'there is no precedent'. Used in formal or business contexts to stress that something is completely new.
この決定は前例がない。
This decision is unheard-of.
Means 'unprecedented' or 'groundbreaking', but often implies eccentric or unconventional. Can be positive or negative.
彼の破天荒な行動に驚いた。
I was surprised by his unheard-of behavior.
An adjective meaning 'outrageous', 'absurd', or 'unthinkable'. Very common in speech.
それはとんでもない間違いだ。
That's an unheard-of mistake.
Means 'must not happen' or 'unacceptable'. Emphasizes that something should never occur.
こんな不正はあってはならない。
Such unheard-of injustice must not happen.
A strong, formal expression meaning 'outrageous' or 'preposterous'. Used for moral condemnation.
彼の行為は言語道断だ。
His actions are unheard-of.
Literally 'not known'. A straightforward way to say something is unheard-of in the sense of lacking recognition.
その町は観光客に知られていない。
That town is unheard-of among tourists.