noun which may take the genitive case particle 'no'
anonymous; of unknown authorship
Used primarily in bibliographic, academic, or literary contexts to indicate that the author of a work is unknown. Often appears as a descriptor for classical texts, poems, or historical documents.
This waka poem is considered to be of unknown authorship.
Many ancient documents of unknown authorship remain.
匿名 means 'anonymous' in the sense of intentionally hiding one's name, often for privacy or safety. 作者未詳 is used when the author's identity is simply unknown, not deliberately concealed.
無名 can mean 'unsigned' or 'anonymous' for works, but also 'unknown' or 'obscure' for people. 作者未詳 is more formal and specifically refers to unknown authorship of a text.
Compound of 作者 (author) and 未詳 (unknown, not yet clear). The term is a Sino-Japanese coinage used in classical bibliography.