saponin

 
Pronunciation: /ˈsapənɪn/

noun

[mass noun] Chemistry
  • a toxic compound which is present in soapwort and makes foam when shaken with water.
  • [count noun] any of the class of steroid and terpenoid glycosides which foam when shaken with water, examples of which are used in detergents and foam fire extinguishers.

Origin:

mid 19th century: from French saponine, from Latin sapo, sapon- 'soap'