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]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "pathfinder":
   adventurer, alpinist, ancestor, announcer, antecedent, astronaut,
   avant-garde, bellwether, buccinator, bushwhacker, camper, climber,
   coach, comers and goers, commuter, cosmopolite, cruiser,
   excursionist, explorer, fare, forebear, foregoer, forerunner,
   front runner, frontiersman, fugleman, globe-girdler, globe-trotter,
   goer, groundbreaker, guide, hajji, harbinger, herald, innovator,
   instructor, jet set, jet-setter, journeyer, lead runner, leader,
   mariner, mentor, messenger, mountaineer, palmer, passenger,
   passerby, pilgrim, pioneer, point, precedent, precursor,
   predecessor, preparationist, preparator, preparer, rubberneck,
   rubbernecker, sailor, scout, sightseer, stormy petrel, straphanger,
   teacher, tourer, tourist, trailblazer, trailbreaker, trainer,
   transient, traveler, trekker, tripper, vanguard, vaunt-courier,
   viator, visiting fireman, voortrekker, voyager, voyageur, wayfarer,
   world-traveler