The Collaborative International Dictionary
cathartin
cathartin \ca*thar"tin\, n. (Chem.) The bitter, purgative principle of senna. It is a glucoside with the properties of a weak acid; -- called also cathartic acid, and cathartina.
Wiktionary
cathartin
n. (context organic compound English) The bitter purgative principle of senna. It is a glucoside with the properties of a weak acid.