| Noun | 1. | senega - dried root of two plants of the genus Polygala containing an irritating saponinPolygala alba, senega - perennial bushy herb of Central and southern United States having white flowers with green centers and often purple crest; similar to Seneca snakeroot root - (botany) the usually underground organ that lacks buds or leaves or nodes; absorbs water and mineral salts; usually it anchors the plant to the ground | |