poison oak

noun

either of two shrubs, Rhus toxicodendron, of the eastern U.S., or R. diversiloba, of the Pacific coast of North America, resembling poison ivy and causing severe dermatitis when touched by persons sensitive to them.

Origin of poison oak

An Americanism dating back to 1735–45

Also called poison ivy.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for poison oak

Historical Examples of poison oak

It is our holly, as the Ceanothus is our lilac, and the poison-oak is our autumn-red sumac.
Insect Stories
Vernon L. Kellogg
The further he goes the worse the jungle of poison-oak and ivy, which at last circles him round in strangling embrace.
Little Journeys to the Homes of the Great, Volume 7
Elbert Hubbard
Here climbed in tantalizing beauty—tempting as insidious vice, which attracts but to destroy—the poison-oak vine.
Memories
Fannie A. (Mrs.) Beers
Just because we use a poison-oak leaf for our brand—why, that's what got 'em to callin' us the Poison Oakers.
The Heritage of the Hills
Arthur P. Hankins
Put the affair of the poison-oak into their hands, and they would lasso every one concerned, with yards of red tape!
The Port of Adventure
Charles Norris Williamson and Alice Muriel Williamson

British Dictionary definitions for poison oak

poison oak

noun

either of two North American anacardiaceous shrubs, Rhus toxicodendron or R. diversiloba, that are related to the poison ivy and cause a similar rashSee also sumach (def. 1)
(not in technical use) another name for poison ivy

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

poison oak in Medicine

poison oak

Either of two shrubs, Rhus toxicodendron of the southeast United States or R. diversiloba of western North America, related to poison ivy and causing a rash on contact.
poison ivy