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

The group rested at the waterfall, including one hiker who put his hand on some poison oak.

From Los Angeles Times ● May 29, 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

Interesting side note: Mugwort tends to grow next to poison oak.

From Los Angeles Times ● Nov. 3, 2024

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

From New York Times ● Dec. 24, 2023

The only thing I couldn’t understand was why it was just poison oak and not a snake or something.

From "The Sound and the Fury" by William Faulkner