Dictionary.net

The juice of the root is extremely acrid and poisonous. What remains, after expressing it, is made into cakes or meal; of which the cassada or cassava bread is formed. This bread constitutes a principal food of the inhabitants of those parts where it grows. The fecula of the root forms Tapioca, which is very nutritious. It may be prepared in the same manner as sago. A factitious Tapioca is met with in the shops, which is in very small, smooth, spherical grains, and is supposed to be prepared from potato starch. It is sold under the name pearl tapioca.

See Cassava.