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

conversion to iteration

   A transformation applied to functional programs to replace
   recursion with iteration.  A tail-recursive function can be
   compiled to an iterative loop where the recursive call becomes
   a jump back to the start and the parameters are held in
   registers which are updated with new values each time around
   the loop.  See Iteration, Tail recursion optimisation.