hoshana rab·bah noun orhoshanah rab·bahorhoshana rab·ba\-ˈrä(ˌ)bä, -_bə\ Usage: usually capitalized H&R Etymology: Aramaic hōsha'nā rabbā : the 7th day of the Festival of Sukkoth observed on the 21st day of Tishri with special prayers and ceremonies in the synagogue by Orthodox and Conservative Jews