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

16 bit

    Using words containing sixteen
   bits.  This adjective often refers to the number of bits
   used internally by a computer's CPU.  E.g. "The Intel 8086
   is a sixteen bit processor".  Its external data bus or
   address bus may be narrower.  The term may also refer to the
   size of an instruction in the computer's instruction set or
   to any other item of data.

   See also 16-bit application.

   (1996-05-13)