What is the meaning of Zwieback?

A form of rusk, 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.

Douglas Harper (2001–2025) “zwieback”, in Online Etymology Dictionary.; though it gives Zweiback as the source.

Source: wiktionary.org