This is a confusing and imprecise term which has been picked up by ultralight backpackers and turned into a religious debate and a weapon for scoring points against one another.
For us practical types, it's how much weight you carry. This depends on how you look at it. Base pack weight is the weight of the pack and everything in it, excluding consumables. Total pack weight is th base pack weight plus food, water, and fuel.
So, any questions?
No? Then get moving already.
Have anything worth adding? Then try sosayseff@gmail.com
Me? Mostly weightless. Waitless. Waistless. Whatever.
Etc...
so says eff: sporadic spurts of grade eff distraction
definitions: outdoor terms
fiyh: dave's little guide to ultralight backpacking stoves
boyb: dave's little guide to backpacks
snorpy bits: nibbling away at your sanity
last seen receding: missives from a certain mobile homer
noseyjoe: purposefully poking my proboscis into technicals