Opposite of a geocacher - a person who does not participate in the game of geocaching. This term is rarely used outside geocaching circles. It comes from the term muggle, a non-magician, in the Harry Potter books. Like muggles, who don't usually know that magic exists, most GeoMuggles don't know that geocaching exists.
Examples of use include: "My first geocache was plundered by a geomuggle two days after I hid it!" and "Be discreet while geocaching - digging around in a Tupperware out in the woods is likely to get odd looks from geomuggles."