poison ivy

noun

1. a vine or shrub, Rhus radicans, having trifoliate leaves and whitish berries and causing severe dermatitis when touched by persons sensitive to it.

2. poison oak.

3. the rash caused by touching poison ivy.

poison ivy

noun

1. any of several North American anacardiaceous shrubs or vines of the genus Rhus (or Toxicodendron ), esp R. radicans, which has small green flowers and whitish berries that cause an itching rash on contact See also sumach

Word History and Origins

Origin of poison ivy¹

An Americanism dating back to 1775–85