The first person to find a letterbox.

The running count of how many letterboxes a letterboxer has found. This number can be controversial since not everyone always agrees on what should count as a find or not.

A flea is a non-restricted form of a cootie. You can plant it in letterboxes as if it was a hitchhiker, or on a person like a traditional cootie. You can log in with a thumbprint signature or use your signature stamps.

A box that people seem to plant for the sake of planting or getting rid of a carve... like it was "flung" out the window of the car.

Flugged. When you missed saying goodbye to someone when they leave the chat room.

An F-summary gives you a proverbial bird's-eye view of the most recent finds and attempts on a letterbox. For instance, it might read something like FFFxxFFxF. The F's represent finds and the x's represent failed attempts, in order from left to right, so this sequence represents a find, find, find, attempt, attempt, find, find, attempt and finally a find.