unidentified
adj.adj. not recognized or known. You use this to describe something that has been seen but nobody knows exactly what it is or who it belongs to.
adj. not recognized or having no established identity. Often used in official, forensic, or scientific contexts to describe objects, persons, or substances whose origins remain unknown.
The police found an unidentified car parked in the driveway.
A small, unidentified object was seen flying over the coast, prompting a brief investigation by the local authorities.
The museum's basement contains several unidentified fragments of pottery that likely date back to the late Bronze Age, though their exact provenance remains a mystery to researchers.
From un- + identified.
Typically used as an attributive adjective before a noun.