poison oak



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. 2019

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.

  • Here climbed in tantalizing beauty—tempting as insidious vice, which attracts but to destroy—the poison-oak vine.


    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


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
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.