poison oak

noun

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

poison oak

noun

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

Word History and Origins

Origin of poison oak¹

An Americanism dating back to 1735–45

Example Sentences

“In 20 years, it’s very likely vegetation that thrives in hot and dry conditions, like poison oak, will see its growing range expand at the expense of plants that have an affinity for wetter, more sheltered site conditions,” Lee said.

From Outside Online

The true poison oak is the Rhus diversiloba of the Western States.

From Project Gutenberg

The sun had not yet climbed the wooded ridges beyond Poison Oak Ranch.

From Project Gutenberg

Just because we use a poison-oak leaf for our brand—why, that's what got 'em to callin' us the Poison Oakers.

From Project Gutenberg

The poison oak had turned from green to brilliant red, and now was dark-green once more.

From Project Gutenberg

And—and when we're—married, you won't take me away from the Poison Oak Country, will you, dear!

From Project Gutenberg