poison ivy

noun

1

a

: a climbing plant (Toxicodendron radicans synonym Rhus radicans) of the cashew family that is especially common in the eastern and central U.S., that has ternate leaves, greenish flowers, and white berries, and that produces an irritating oil causing a usually intensely itching skin rash

b

: any of several plants closely related to poison ivy

2

: a skin rash caused by poison ivy

Illustration of poison ivy

• poison ivy 1a

Examples of poison ivy in a Sentence

I got poison ivy all over my arm.

Recent Examples on the Web

There was poison ivy in the front yard, the sidewalk had cracks, and there was garbage everywhere. —Celia Fernandez, CNBC, 25 Apr. 2025

But scratching an itch, especially one as intense as that caused by poison ivy, is nigh irresistible — and feels so satisfying. —Avery Hurt, Discover Magazine, 29 Mar. 2025

Oftentimes, so is the tough shell that surrounds the nut, which contains a toxic resin called urushiol, which is also found in poison ivy. —New Atlas, 26 Mar. 2025

Newsletter Sign up for our email newsletter for the latest science news Listen to this Article Ever had poison ivy? —Avery Hurt, Discover Magazine, 29 Mar. 2025

Word History

First Known Use

1782, in the meaning defined at sense 1a

Kids Definition

poison ivy

noun

1

: a usually climbing plant that is related to the sumacs, has leaves usually with three leaflets, greenish flowers, white berries, and leaves and stems that when bruised and touched may cause an itching rash on the skin

2

: a skin rash caused by poison ivy

Medical Definition

poison ivy

noun

-ˈī-vē 

1

a

: a climbing plant of the genus Rhus (R. radicans synonym Toxicodendron radicans) that is especially common in the eastern and central United States, that has leaves in groups of three, greenish flowers, and white berries, and that produces an acutely irritating oil causing a usually intensely itching skin rash

b

: any of several plants closely related to poison ivy

especially : poison oak sense 1b

2

: a skin rash produced by poison ivy