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

Not to mention poison oak and killer bees and the potential for the hillside to give way and crush everything below it. —T. Coraghessan Boyle, New Yorker, 14 Sep. 2025

Hikers could use the Outdoor Lens tool to capture potential interactions with poison ivy or poison oak, for example, or even dangerous insects. —Michael Cappetta, Travel + Leisure, 11 Sep. 2025

On a recent visit, native flowers were prominent along the shaded pathway, as were numerous growths of poison oak. —Don Sproul, Oc Register, 9 Sep. 2025

Poison sumac and poison oak are also related to poison ivy and can cause a rash when touched. —Sarah Moore, Freep.com, 23 Aug. 2025

Word History

First Known Use

1739, in the meaning defined at sense 1

Rhymes for poison oak

• artichoke
• nanticoke
• womenfolk
• awoke
• baroque
• bespoke
• colloque
• convoke
• evoke
• invoke
• keystroke
• kinfolk

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 

1

: any of several plants included in the genus Rhus or sometimes in the genus Toxicodendron that produce an irritating oil like that of poison ivy:

a

: a bushy plant (R. diversiloba synonym T. diversilobum) of the Pacific coast

b

: a bushy plant (R. toxicodendron synonym T. pubescens) of the southeastern United States

2

: poison ivy sense 1a

3

: a skin rash produced by poison oak