Source : WordNet®

cookie jar
     n : a jar in which cookies are kept (and sometimes money is
         hidden) [syn: {cooky jar}]

Source : Free On-Line Dictionary of Computing

cookie jar
     
        1.  An area of memory set aside for storing
        {cookies}.  Most commonly heard in the {Atari ST} community;
        many useful ST programs record their presence by storing a
        distinctive {magic number} in the jar.  Programs can inquire
        after the presence or otherwise of other programs by searching
        the contents of the jar.
     
        2.  A {cracker} term for the password file of a
        multi-user computer.
     
        [{Jargon File}]
     
        (1997-02-12)