Source : Webster's Revised Unabridged Dictionary (1913)

Haversack \Hav"er*sack\, n. [F. havresac, G. habersack, sack for
   oats. See 2d {Haver}, and {Sack} a bag.]
   1. A bag for oats or oatmeal. [Prov. Eng.]

   2. A bag or case, usually of stout cloth, in which a soldier
      carries his rations when on a march; -- distinguished from
      knapsack.

   3. A gunner's case or bag used carry cartridges from the
      ammunition chest to the piece in loading.

Source : WordNet®

haversack
     n : a bag carried by a strap on your back or shoulder [syn: {backpack},
          {back pack}, {knapsack}, {packsack}, {rucksack}]