a buckthorn tree or shrub of the Pacific coast of the USA: Rhamnus purshiana. Also called cascara buckthorn
the dried bark of this a buckthorn tree or shrub of the Pacific coast of the USA, used as a mild laxative. Also called cascara sagrada
[Spanish cáscara bark, from cascar to crack, break, from Latin quassare to shake, break; (sense 2) American Spanish cascara sagrada sacred bark]