Wordnet 3.0
NOUN (1)
1. 
 letter carrier's shoulder bag; 
- Example: "in Britain they call a mailbag a postbag"[syn: mailbag, postbag]
WordNet (r) 3.0 (2006):
postbag
    n 1: letter carrier's shoulder bag; "in Britain they call a
         mailbag a postbag" [syn: mailbag, postbag]