Rusk and Zwieback

Rusk noun - Slice of sweet raised bread baked again until it is brown and hard and crisp.

Zwieback is a synonym for rusk. In some cases you can use "Zwieback" instead a noun "Rusk".

Zwieback noun - Slice of sweet raised bread baked again until it is brown and hard and crisp.

Rusk is a synonym for zwieback. (British) You can use "Rusk" instead a noun "Zwieback".