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

floating-point accelerator

    (FPA) Additional hardware to perform functions on
   floating point numbers such as addition, multiplication,
   logarithms, exponentials, trigonometric functions and
   various kinds of rounding and error detection.  A floating
   point accelerator often functions as a co-processor to the
   CPU.

   The term "floating-point accelerator" suggests a physically
   larger system, often an extra circuit board, whereas a
   "floating-point unit" is probably a single chip or even part
   of a chip.

   (1994-12-01)