Lacking a name; not named, for example an animal not assigned to any species.
Without any name acknowledged of a person responsible
"an anonymous pamphlet; an anonymous subscription."
"an anonymous author; an anonymous benefactor."
"The anonymous contributors of Wikipedia"
"No customer personal data will be retained unless it is rendered anonymous."
"an anonymous office block in a soulless industrial estate''"
a person who posts to an online forum, or otherwise distributes information anonymously
Nameless; of unknown name; also, of unknown or unavowed authorship; as, an anonymous benefactor; an anonymous pamphlet or letter.
having no known name or identity or known source;
"an anonymous gift"
not known or lacking marked individuality;
"brown anonymous houses"
"anonymous bureaucrats in the Civil Service"