urushiol

American  

[oo-roo-shee-awl, -ol] / ʊˈru ʃiˌɔl, -ˌɒl /

noun

1. a toxic, liquid, catechol derivative, the active irritant principle in several species of the plant genus Rhus, as in poison ivy.

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urushiol British  

/ uːˈruː-, ˈuːrʊʃɪˌɒl /

noun

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

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urushiol Scientific  

/ -ro̅o̅′shē-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.

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Etymology

Origin of urushiol

1910–15; < Japanese urushi lacquer + -ol ¹

Example Sentences

The oily substance it contains, urushiol, tends to cause more intense reactions over time and it affects up to 90 percent of people.

From National Geographic • Apr. 18, 2023

In the past, dermatologists believed that urushiol rashes and itch were triggered by the immune system's T cells, which rally antibodies to attack the skin irritant.

From Scientific American • Sep. 20, 2021

You can occasionally see the urushiol oil as black spots on poison ivy leaves.

From Washington Post • Sep. 10, 2021

Researchers also found that CO2 makes urushiol, the oil in poison ivy that causes the allergic reaction in humans, stronger.

From Salon • Jul. 29, 2021

The Forest Service found that between 70 and 85 percent of the population is sensitive to urushiol, and people are likely to become more allergic to it every time they are exposed.

From Salon • Jul. 29, 2021