- a Chilean tree, Quillaja saponaria, of the rose family, having evergreen leaves and small, white flowers.
- the inner bark of this tree, used as a substitute for soap.
- a W South American rosaceous tree, Quillaja saponaria, with undivided evergreen leaves and small white flowers
- the inner bark of this tree, formerly used as soap and as a source of saponin
- any of several trees or shrubs that have a bark similar to this
