rusk

Etymology

Spanish or Portuguese rosca (“a twist or roll of bread”)

noun

1. a rectangular, hard, dry biscuit
2. a twice-baked bread, slices of bread baked until they are hard and crisp (also called a zwieback)
   A newly-arrived couple at the next table […] admitted that “this was more like” and that if the Alpenrose could also produce a proper cup of tea it would be just like home. Bill Andreyef, who was eating a lightly-boiled egg and a rusk, regarded the other diners with resentment. 1956, Delano Ames, chapter 25, in Crime out of Mind
3. a weaning food for children
4. a cereal binder used in meat product manufacture