书牍 shūdú correspondence Origin Definitions Defs Strokes Stroke Words Sentences Sents shūdú correspondence 书 書 shū noun letter a letter; mail or correspondence牍 牘 dú document (bound form) official document; letter; bookshūdú ancient documents 书 書 shū noun document a formal document, certificate, or written statement牍 牘 dú writing tablet (bound form) wooden tablet or slip used for writing in ancient times