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Gregory's powder

noun
  1. a formulation of rhubarb powder used as a laxative or purgative

Word Origin for Gregory's powder

C19: named after Dr James Gregory (1753–1821), who first made it
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012