The bark of the root of a tropical American tree of the genus Simarouba (more fully "simarouba bark"); a bitter tonic made from this, used especially as a treatment for dysentery and diarrhoea.

Any of the tropical American trees and shrubs of the genus Simarouba (family Simaroubaceae), the members of which have alternate, pinnately compound leaves and small unisexual flowers borne in panicles; specifically the large tree S. amara.