Day Packs --  a smaller, lighter weight bag constructed to hold the supplies needed for a single day’s hike 

Dehydrated Foods – food items with the water removed (such as beef jerky and dried fruit) are lighter weight and longer lasting than conventional foods, and therefore make a great provision for long hikes; see also “Freeze Dried Food”

 
Denier – abbreviated as “D” a measurement of fabric density; the weight of the material in grams per 1000 meters length (i.e., a fabric with 5d  weighs 5 grams per 1000 meters length)
 
Down – a fabric insulation made of geese feathers, soft, light weight and warm, down is often used in sleeping bags, coats, etc. 
 
 Elongation – a foot condition which lengthens the foot, caused by heavy duty walking or weight on a too-flexible arch
 
 Expedition Packs – the largest type of backpacks meant to carry the equipment and supplies needed for a multiple
 
From the Skin Out (FSO) -- the added weight to your body by your clothing and equipment; in other words the weight of everything outside yourself.