Pathfinder Syllabification: (Path·find·er)Pronunciation: /ˈpaTHˌfīndər/ (in full Mars Pathfinder)Definition of Pathfinder an unmanned American spacecraft that landed on Mars in 1997, deploying a small robotic rover (Sojourner) to explore the surface and examine the rocks. Pathfinder in other Oxford dictionaries Definition of Pathfinder in the British & World English dictionary