zwie·back (swē'bāk', -bäk', swī'-, zwē'-, zwī'-) n. A usually sweetened bread baked first as a loaf and later cut into slices and toasted.
[German : zwie-, twice (from Middle High German zwi-, from Old High German; see dwo- in Indo-European roots) + backen, to bake (from Middle High German, from Old High German bahhan, backan).]