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

iterator

    An object or routine for accessing items
   from a list, array or stream one at a time.

   By extension, the term can be used for an object or routine
   for accesing items from any data structure that can be viewed
   as a list.  For example, a traverser is an iterator for
   tree-shaped data structures.

   (2001-10-04)