The crossword solution for the term 'IS RETROCESSIVE' is EBBS, which stands for 'Ebb and Flow System'. This is a type of water management system that uses the natural flow of water to regulate the amount of water in a given area. It works by allowing water to flow in and out of an area, depending on the tide or other environmental factors. This system is often used to manage water resources in coastal areas, as it helps to maintain a balance between the amount of water available and the amount of water needed.