poison oak

noun

1
: any of several plants related to poison ivy and producing an oil with similar irritating properties: such as
a
: a bushy plant (Toxicodendron diversilobum synonym Rhus diversiloba) of the Pacific coast
b
: a bushy plant (Toxicodendron pubescens synonym Rhus toxicodendron) chiefly of the southeastern U.S.
2
: poison ivy sense 1a

Examples of poison oak in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
But on top of it, have poison oak on my manly parts. — Outside Online, 18 Feb. 2026 The trail does pass over a small flowing creek, but keep an eye out for poison oak near the water. — Maura Fox, San Diego Union-Tribune, 27 Mar. 2026 Do keep an eye out for poison oak, which appears to be thriving in some creekside areas. — John Metcalfe, Mercury News, 4 May 2026 But remember that on poison oak and poison ivy, the top leaf will always have a longer stem. — New York Times, 16 May 2026 See All Example Sentences for poison oak

Word History

First Known Use

1739, in the meaning defined at sense 1

Time Traveler
The first known use of poison oak was in 1739

Rhymes for poison oak

See All Rhymes for poison oak

Browse Nearby Words

poison nut
poison oak
poisonous
See all Nearby Words

Cite this Entry

“Poison oak.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/poison%20oak. Accessed 7 Jul. 2026.

Copy Citation

Kids Definition

poison oak

noun
: any of several shrubby plants related to poison ivy and causing a similar rash

Medical Definition

poison oak

noun
-ˈōk How to pronounce poison oak (audio)
1
: any of several plants included in the genus Toxicodendron that produce an irritating oil like that of poison ivy:
a
: a bushy plant (T. diversilobum synonym R. diversiloba) of the Pacific coast
b
: a bushy plant (T. pubescens synonym R. toxicodendron) of the southeastern United States
2
: poison ivy sense 1a
3
: a skin rash produced by poison oak

More from Merriam-Webster on poison oak

Britannica.com: Encyclopedia article about poison oak

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