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

From unique fauna to poison ivy, trails may have a variety of features to pique a traveler’s curiosity. —Michael Cappetta, Travel + Leisure, 11 Sep. 2025

Even under Joe Biden — who was as green as poison ivy — oil and gas production hit new highs. —Stephen Moore, Boston Herald, 21 Aug. 2025

Manjack was slowed with a bad case of poison ivy at the beginning of fall camp, but finally got back into the mix and had his best practice Saturday. —Steven Johnson, Fort Worth Star-Telegram, 17 Aug. 2025

When the hiker suggested a shortcut through the poison ivy, the others said — SCRATCH THAT! —Usa Today, USA Today, 15 Aug. 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