Being or having an unknown or unnamed source:
— An unnamed donor.

synonyms: nameless, unidentified, unknown.

Roget 565: misnamed etc. v.; pseudonymous; soi-disant [Fr.]; self called, self styled, self christened; so-called.    nameless, anonymous; without a having no name; innominate, unnamed; unacknowledged.    ... show more

Polish: bezimienny