This is the 13755th most frequent Russian word.
неустановленной
"Unidentified" or "unestablished."
Describes an unresolved or undetermined state regarding a specific cause.
Причина аварии осталась неустановленной.
The cause of the accident remained unestablished.
Refers to sources that are anonymous or not validated.
В докладе были указаны неустановленные источники информации.
The report mentioned unidentified sources of information.
Used to indicate an undefined or unspecified attribute, here nationality.