hardtack

1. (nautical) A large, hard biscuit made from unleavened flour and water; formerly used as a long-term staple food aboard ships.Examples: "Meronym: reefer's nut"; "Philander went into the next room[…]and came back with a salt mackerel that dripped brine like a rainstorm. Then he put the coffee pot on the stove and rummaged out a loaf of dry bread and some hardtack."; "Bread and fodder had to be brought up over longer and longer distances, it was more difficult all the time, transport was lacking, the army had already eaten two-thirds of its hardtack, exhausted men were marching in baking heat along sandy roads into emptiness!"Synonyms: pilot biscuit, pilot bread, sea biscuit, sea bread, ship's biscuit, ship biscuit, ship bread, ;countableuncountable