Haversack
Part of speech: noun
Definition: A small, strong bag carried on the back or the shoulder, usually with only one strap. Originally made of canvas. oat-sack, or nose-bag for a horse.
Knapsack
Part of speech: noun
Definition: A case of canvas or leather, for carrying items on the back.
Part of speech: verb
Definition: To go hiking while burdened with a knapsack, usually overnight (or longer.)