a.

1. 匿名的；姓氏不明的
   We received an anonymous letter.

   我们收到一封匿名信。

2. 出自无名氏之手的；来源不明的
   An anonymous author wrote this book.

   这本书出自无名氏之手。

3. 无特色的，无个性特征的
   the anonymous buildings

   外观千篇一律的楼房

adj.

1. not identified by name; of unknown identity:
   an anonymous phone call.
2. having no individual or unusual features.