Source : Free On-Line Dictionary of Computing

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)