Translation guide
How to express that something is not known, unfamiliar, or unidentified in Japanese.
The most common way to say 'I don't know' about a fact or piece of information. Casual.
I don't know about that.
I don't know where he is.
Polite form of 知らない. Use in formal situations or with strangers.
Sorry, I don't know.
Literally 'I don't understand', but often used like 'I don't know' when the answer isn't clear or you haven't figured it out.
I don't know the answer.
Formal/written term meaning 'unknown' or 'unidentified'. Often used in reports or news.
The cause is unknown.
Describing something whose identity, name, or nature is not known.
Used for mysterious objects, creatures, or people whose true identity is unknown.
An unidentified creature was discovered.
Specifically for a person whose identity (name, background) is unknown, e.g., a John Doe.
Means 'unknown' in the sense of not yet discovered or explored. Often used in science or exploration.
Describing a person, place, or thing that is not well-known or recognized.
While 不明 means 'unknown', it is formal and often used in written contexts. In everyday speech, use 知らない or 分からない instead.
That is unknown. (overly formal for casual chat)
An unidentified body was found.
an unknown virus