poison oak

American  

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.

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poison oak British  

noun

1. 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. (not in technical use) another name for poison ivy

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Etymology

Origin of poison oak

An Americanism dating back to 1735–45

Example Sentences

See Examples For:

poison oak

Once you’re above the residential lots, you’ll see pipes along the way, carrying water down the hill, along with occasional trailside poison oak.

From Los Angeles Times ● Jan. 5, 2026

Poodle-dog isn’t a household name like poison oak and ivy, likely due to its limited geographic region and fleeting nature.

From Los Angeles Times ● Apr. 5, 2025

If contact is suspected, trail restorer Blaker recommends treating it like poison oak and scrubbing the affected skin with a degreaser.

From Los Angeles Times ● Apr. 5, 2025

Its sparse plant life consists of scraggly shrubs and pines, along with thickets of poison oak.

From New York Times ● Dec. 24, 2023

And then the frantic morning winds began to twist along the ground, and a chill came into the air, and the poison oak turned red.

From "The Red Pony" by John Steinbeck