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

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

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

This plant tends to give people a more intense allergic skin reaction than poison oak, said Trimble.

From Los Angeles Times • May 24, 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