zwieback

Etymology

From German Zwieback, from zwie- (“twi-, two-”) + backen (“to bake”) (i.e “twice-baked”), a calque of Italian biscotto (but not to be confused with it).

noun

1. A usually sweetened bread enriched with eggs that is baked and then sliced and toasted until dry and crisp; considered easy to digest and therefore given to the ill and used as a teething food for toddlers.
   Ogden Nash, Adventures Of Isabel She nibbled the zwieback that she always fed off, And when it was gone, she cut the giant's head off.