a North American milkweed, Asclepias tuberosa, whose root was used as a remedy for pleurisy.
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Origin of pleurisy root
An Americanism dating back to 1775–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for pleurisy root
the root of the butterfly weed, formerly used as a cure for pleurisy
another name for butterfly weed
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