The term SENNA can be broken down into two crossword solutions: CASSIA (6 letters) and PURGE (5 letters). CASSIA is a genus of flowering plants in the legume family, Fabaceae, native to tropical and subtropical regions throughout the world. The seeds of some species are used as a traditional medicine and as a flavoring agent. PURGE is an act of removing something, usually unwanted or unpleasant, from a place or situation. It is often used to describe the removal of unwanted people or ideas from a society or organization.