Nameless (9)
'nameless' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for anonymous that I've seen before include "Nameless" , "Of unknown identity" , "Having no known name" , "Unaccredited" , "Not identified by name" .)
'nameless' is the definition.
(I know that nameless can be written as unknown)
This is the entire clue.
(Other definitions for unknown that I've seen before include "Anonymous" , "Obscure; x, say, in equation" , "Unidentified - not explored" , "Unidentified, strange" , "Mysterious" .)