Definition of "trailhead"

trailhead

noun
plural trailheads
1. The beginning of a trail, often specifically a hiking trail.
  Quotations
  Take a bus or a cab to the trailhead, and walk a couple of hours to the magnificent, cow-inhabited Tai Long Wan beach.
  2010 January 22, Krista Mahr, “Authentic Asian Experiences (Round II): See Hong Kong's Greener Side”, in Time‎, retrieved 13 August 2016
2. (gaming) The initial clue that leads to an alternate reality game.
  Quotations
  The trailhead can be exposed to potential gamers through social network services, websites, emails, or sometimes non-electronic media.
  2017, Sangkyun Kim, Kibong Song, Barbara Lockee, John Burton, Gamification in Learning and Education, Springer, page 27