Definitions:
originally: the sumac, rhus coriaria, of southern europe. in later use: any of numerous small trees, shrubs, and climbers constituting the genus rhus (family anacardiaceae), which are characterized by milky, often irritant, latex and which include many allergenic plants as well as the sumac and the staghorn sumac, r. hirta (formerly r. typhina), grown as an ornamental. also (in form rhus): the genus itself.