hardtack definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
unleavened bread made in very hard, large wafers: it was formerly a part of army and navy rations
Origin: hard plush tack,
hardtack definition by American Heritage Dictionary
A hard biscuit or bread made with only flour and water. Also called sea biscuit, sea bread, ship biscuit.