Our good friend and founder of the Preppers Networks, Riverwalker, posted his definition of a prepper on his blog Stealth Survival. I think this is one of the best definitions of the word I have read. It embodies all preppers, no matter if you're an established homesteader or getting started with a few extra weeks of food. Read Riverwalker's definition below, and let us know in the comments if you agree with his take on what a prepper is.
Definition of a Prepper
Prepper (noun): An individual or group that prepares or makes preparations in advance of or prior to any change in normal circumstances or lifestyle without significant reliance on other persons (i.e., being self-reliant) or without substantial assistance from outside resources (govt., etc.) in order to minimize the effects of that change on their current lifestyle.