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

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Example Sentences

See Examples For:

poison oak

The reaction is often likened to the reaction to poison oak and ivy, though some say it’s worse.

From Los Angeles Times ● Apr. 5, 2025

He likely traipsed through poison oak while out in the wilderness and the swelling in his paws had not subsided as of Thursday, Dawes said.

From Los Angeles Times ● Jul. 18, 2024

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

From New York Times ● Dec. 24, 2023

BY COMPARISON, “the fox war” seems rather like fighting to protect dandelions and poison oak in a rare-plant garden.

From Seattle Times ● Aug. 4, 2023

There’s poison oak on this island and I don’t want us to get it.

From "Al Capone Does My Shirts" by Gennifer Choldenko

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