- either of two shrubs, Rhus toxicodendron, of the eastern United States, or R. diversiloba, of the Pacific coast of North America, resembling poison ivy and causing severe dermatitis when touched by persons sensitive to them.
- either of two North American anacardiaceous shrubs, Rhus toxicodendron or R. diversiloba, that are related to the poison ivy and cause a similar rash
- (not in technical use) another name for poison ivy
