• synonyms


[oo-roo-shee-awl, -ol]
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  1. a toxic, liquid, catechol derivative, the active irritant principle in several species of the plant genus Rhus, as in poison ivy.

Origin of urushiol

1910–15; < Japanese urushi lacquer + -ol1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for urushiol


  1. a poisonous pale yellow liquid occurring in poison ivy and the lacquer tree

Word Origin

from Japanese urushi lacquer + -ol ²
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

urushiol in Medicine


(u-rōōshē-ôl′, -ōl′)
  1. A toxic substance constituting the active allergen of the irritant oil present in poison ivy, poison oak, and poison sumac.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

urushiol in Science


[u-rōōshē-ôl′, -ōl′]
  1. A toxic substance present in the resin or on the surface of plants of the genus Rhus (syn. Toxicodendron). Urushiol is a mixture of several derivatives of catechol and is the irritating substance in poison ivy.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.