"Hard tack, pilot bread, ship's biscuit, shipbiscuit, sea biscuit, cabin bread, sea bread, dog biscuit, tooth dullers, sheet iron, worm castles, molar breakers"@en . . . "Hardtack"@en . . "Flour,water" . . "Hardtack (or hard tack) is a simple type of cracker or biscuit, made from flour, water, and sometimes salt. Inexpensive and long-lasting, it was and is used for sustenance in the absence of perishable foods, commonly during long sea voyages and military campaigns."@en . . .