sumac or sumach (shū'măk, sū'–) , common name for some members of the Anacardiaceae, a family of trees and shrubs native chiefly to the tropics but ranging into north temperate regions and characterized by resinous, often acrid, sap. The sap of certain of these plants—especially poison ivy and related species of the New World genus Toxicodendron—contains an essential oil that can cause dermatitis.

The fruit form dense clusters of reddish drupes.

The hairy covering of the drupes is harvested and used as a spice in some Middle-Eastern countries. In North America, the smooth sumac, Rhus glabra, and the staghorn sumac, Rhus typhina, are sometimes used to make a beverage, termed "sumac-ade" or "Indian lemonade" or "rhus juice". This drink is made by soaking the drupes in cool water, rubbing the active principle off the drupes, then straining the liquid through a cotton cloth and sweetening it.