From Low German knapzak or Dutch knapzak (older form cnapsack), from Middle Dutch cnappen (“to bite with teeth”), ultimately from knappen (“to eat, crack”), of imitative origin, + sack. German Knappsack is from Dutch.
knapsack (plural knapsacks)
- (chiefly US) A case of canvas or leather, for carrying items on the back.
- (cryptography) A set of values from which a subset is chosen.
- To go hiking while burdened with a knapsack, usually overnight or for longer.
- My sleeping bag fell off my backpack into the water, while we were knapsacking up the mountain.
- Oxford English Dictionary, 1884–1928, and First Supplement, 1933.