What does the word hardtack mean?

Usage examples for hardtack

  1. I certainly do long sometimes for the good pumpkin and apple pies which I used to have at home, and confess that a little apple sauce would make my hardtack a little more savory. – Frank's Campaign or the Farm and the Camp by Horatio Alger, Jr.
  2. From your hardtack and your straw bed? – The Ego and His Own by Max Stirner
  3. By the light of the brilliant moon we made coffee, called George and Steve and ate our breakfast of cold salmon and hardtack. – The Lure of the Labrador Wild by Dillon Wallace