Pronunciation: (sen'u),[key] —n. 1. any plant, shrub, or tree belonging to the genus Cassia, of the legume family, having pinnate leaves and large clusters of flowers.
2. any of various cathartic drugs consisting of the dried leaflets of certain of these plants, as one drug (Alexandrian senna) derived from C. acutifolia, or another (Tinnevelly senna) derived from C. angustifolia. 3. See wild senna.