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.
A common, emphatic word meaning 'unprecedented' or 'unheard-of in history'. Used for shocking events or situations.
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.
I've never heard of such a thing.
Means 'unprecedented' or 'record-breaking', often used for disasters or crises. More formal and written.
An unheard-of catastrophe occurred.
Means 'there is no precedent'. Used in formal or business contexts to stress that something is completely new.
This decision is unheard-of.
Means 'unprecedented' or 'groundbreaking', but often implies eccentric or unconventional. Can be positive or negative.
I was surprised by his unheard-of behavior.
To express that something is so bad or unacceptable that it is beyond normal experience.
An adjective meaning 'outrageous', 'absurd', or 'unthinkable'. Very common in speech.
That's an unheard-of mistake.
Means 'must not happen' or 'unacceptable'. Emphasizes that something should never occur.
Such unheard-of injustice must not happen.
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.
He is still an unheard-of singer.
Literally 'not known'. A straightforward way to say something is unheard-of in the sense of lacking recognition.
That town is unheard-of among tourists.
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 strong, formal expression meaning 'outrageous' or 'preposterous'. Used for moral condemnation.
His actions are unheard-of.