Root and Branch is an idiom that means to do something completely and thoroughly. It is often used to describe a COMPLETE overhaul or reform of something, such as a system or policy. The term is derived from the Bible, where it is used to describe God's judgment. In the crossword, the solutions for the term Root and Branch are ALL, which stands for 'all-encompassing' or 'COMPLETE'. This emphasizes the idea of doing something completely and thoroughly.