Translation guide
Describes something whose identity, origin, or nature is unknown or not yet determined. Japanese uses different expressions depending on whether you're talking about a person, object, phenomenon, or formal status.
unidentified flying object
To say that something or someone has not been identified, often in news, reports, or formal contexts.
To refer to someone whose name or identity you don't know in everyday conversation.
To describe something seen or detected that cannot be identified, like a flying object or signal.
身元不明 is used for legal/social identity (name, address, etc.), while 正体不明 is for true nature or form, often with a mysterious nuance. 身元不明 is common in police reports; 正体不明 is common in supernatural or speculative contexts.
unidentified body
unidentified monster
Emphasizes that the true nature or identity is unknown, often with a nuance of mystery or suspicion. Used for people, creatures, or phenomena.
An unidentified creature was sighted.
Unconfirmed information is circulating.
見知らぬ男が話しかけてきた。
An unidentified man spoke to me.
An unidentified object was floating in the sea.