Source : Webster's Revised Unabridged Dictionary (1913)

Saponin \Sap"o*nin\, n. [L. sapo, -onis soap: cf. F. saponine.]
   (Chem.)
   A poisonous glucoside found in many plants, as in the root of
   soapwort ({Saponaria}), in the bark of soap bark
   ({Quillaia}), etc. It is extracted as a white amorphous
   powder, which occasions a soapy lather in solution, and
   produces a local an[ae]sthesia. Formerly called also
   {struthiin}, {quillaiin}, {senegin}, {polygalic acid}, etc.
   By extension, any one of a group of related bodies of which
   saponin proper is the type.