[poison ivy] n (1784) 1 a: a climbing plant (Rhus radicans) of the cashew family that is esp. 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 usu. intensely itching skin rash b: any of several plants (as poison oak) closely related to poison ivy
2: a skin rash caused by poison ivy