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

rapid prototyping

    The creation of a working model of a software module
   to demonstrate the feasibility and suitability of the function.
   The prototype is expected to be replaced or refined before
   inclusion in the final product.

   Rapid prototyping contrasts with a DIRFT approach which
   emphasises careful design and implementation to avoid the
   overheads of debugging and testing prototype code.  Rapid
   prototyping is appropriate when the requirements are unclear or
   likely to change (which is most of the time).

   (2012-11-17)