A letterbox designed to be found at night, usually through the use of glow-in-the-dark paint or FireTacks.

A non-boxer, often referred to as a muggle. Noxers can often be recognized on the trail by their clean fingers, inattention to small piles of rocks and clumps of leaves, and complete lack of crumpled papers clutched in their hands.

Short for National Park Service, vilified by letterboxers for their staunch opposition to letterboxes in land under their control.