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

16-bit application

    Software for MS-DOS or Microsoft
   Windows which originally ran on the 16-bit Intel 8088 and
   80286 microprocessors.  These used a segmented address
   space to extend the range of addresses from what is possible
   with just a 16-bit address.  Programs with more than 64
   kilobytes of code or data therefore had to waste time
   switching between segments.  Furthermore, programming with
   segments is more involved than programming in a flat address
   space, giving rise to warts like memory models in C and
   C++.

   Compare 32-bit application.

   (1996-04-06)