The Collaborative International Dictionary of English v.0.48:

briefcase \brief"case\ n.
   a small suitcase with a handle; it is used for carrying
   papers or files or books.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

briefcase
    n 1: a case with a handle; for carrying papers or files or books

The Free On-line Dictionary of Computing (30 December 2018):

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)