The Collaborative International Dictionary of English v.0.48:

Pathfinder \Path"find`er\, n.
   One who discovers a way or path; one who explores untraversed
   regions.
   [1913 Webster]

         The cow is the true pathfinder and pathmaker. --J.
                                                  Burroughs.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pathfinder
    n 1: someone who can find paths through unexplored territory
         [syn: scout, pathfinder, guide]