The prefix geo, for Earth, was used to describe the global nature of this activity, but also for its use in familiar topics in gps such as geography.
Caching, from the word cache, is a french word invented in 1797, the original definition referred to a hiding place someone would use to temporarily store items. The word cache stirs up visions of pioneers, gold miners, and even pirates.
The combination of Earth, hiding, and technology made geocaching an excellent term for the activity. However the “GPS Stash Hunt” was the original and most widely used term until Mike Teague passed the torch to Jeremy Irish in September 2000.