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1. Either of two plants, Toxicodendron pubescens, a shrub of the southeast United States, or T. diversilobum, a shrub or vine of western North America, having compound leaves with three lobed or toothed leaflets, and causing a rash on contact.
2. See poison ivy.
3. A skin rash caused by contact with one of these plants.
Public health A popular term for any allergic reaction or dermatopathy caused by Rhus diversilobium or Rhus diversiloba
poison oakA type of hypersensitivity dermatitis caused by Rhus diversiloba–western poison oak, and R quercifolia–eastern poison oak. See Poison ivy.
poi·son i·vy, poison oak , poison sumac (poy'zŏn ī'vē, ōk, sūmak)
1. See: Toxicodendron
2. Common name for the cutaneous eruption caused by contact with these species of Toxicodendron.
A climbing vine, Toxicodendron diversiloba, closely related to poison ivy and having the same active substances.See: illustration