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

Here's how to smother poison ivy: Cover the poison ivy with a large plastic tarp and leave it in place for a week. —Patricia Shannon, Southern Living, 17 June 2025

Mast cells are activated by allergens (poison ivy, for example), causing inflammation and itching. —Avery Hurt, Discover Magazine, 29 Mar. 2025

About 18 years ago, thick poison ivy covered 64 headstones in Staten Island’s Baron Hirsch Cemetery, including the one belonging to Beckie Neubauer, a 19-year-old Austrian immigrant who died in the Triangle shirtwaist factory fire. —Maria Cramer, New York Times, 16 Feb. 2025

Manual Removal Techniques Start by wearing work gloves, protective clothing, and eyewear especially if the vine contains toxic sap (poison ivy). —Mary Marlowe Leverette, Southern Living, 14 June 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