Source : WordNet®

briefcase
     n : a case with a handle; for carrying papers or files or books

Source : Free On-Line Dictionary of Computing

briefcase
     
         A {Win95}/{WinNT} utility for keeping files on two
        computers without permanent connection in sync.
     
        The scenario briefcase was designed for is the combination of
        an office computer and a {portable} one.  You connect the two
        before leaving your office, create a briefcase on the portable
        (if you don't already have one on it), then copy the files you
        want to work on while away into the briefcase.  You can at
        this point disconnect the two computers, take the portable
        with you and work on the files in the briefcase at home or on
        the road.  When you get back to your office the briefcase
        utility can automatically update the files you changed on the
        office computer.
     
        (1998-05-18)