POISON IVY

noun Date: 1784 1. a climbing plant ( Toxicodendron radicans syn. 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 acutely irritating oil causing a usually intensely itching skin rash, any of several plants closely related to ~, a skin rash caused by ~