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. 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

Word History and Origins

Origin of poison oak¹

An Americanism dating back to 1735–45

Example Sentences

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

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“My feet were torn and oozing within my elk leather boots, and every inch of my skin was a rash of poison oak. Hours before I had been incapacitated by muscle cramps.”

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Rangers describe the trail — a steep half-mile to reach the cave, then a half-mile loop inside — as “strenuous,” featuring possible encounters with poison oak, bees, rattlesnakes and falling rocks.

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

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“So we have six habitats here,” the retired family physician said, giving a dozen of us a quick warning about poison oak before breaking down the marine, plant and wildlife glories that surrounded us.

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