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

Beth Smith lives and runs in Burlingame, California, and runs roads and trails while trying to not get Prednisone-level poison oak rashes. —Lisa Jhung, Outside Online, 15 Nov. 2024

Interesting side note: Mugwort tends to grow next to poison oak. —Jeanette Marantos, Los Angeles Times, 3 Nov. 2024

Similar elastic bands at the ankles make for a secure fit, perfect for pulling over socks in areas where the poison ivy or poison oak hasn’t died back yet or to limit your chances of ticks. —Alice Bennett, Travel + Leisure, 28 Sep. 2024

Like its cousins, poison oak and poison ivy, poison sumac contains urushiol in every part of the plant, but is more toxic. —Leanne Potts, Better Homes & Gardens, 28 Sep. 2024

Word History

First Known Use

1739, in the meaning defined at sense 1

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