Definition of "urushiol" [urushiol]

• A toxic substance present in the resin or on the surface of plants of the genus Rhus, including poison ivy and the lacquer tree, from which a black Japanese lacquer is obtained. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• ""urushiol" (from the Japanese word for lacquer, urushi)."
• "* All of these leafy plants contain an oil called urushiol that is irritating to 50 percent to 75 percent of us."
• "You know, it's the oil sap in poison ivy called urushiol that causes those painful rashes."