Re ebb and flow is a term used to describe the cyclical movement of the tides. It is a phenomenon caused by the gravitational pull of the moon and sun on the Earth's oceans. The term is often used metaphorically to describe the rise and fall of other things, such as emotions or fortunes. The crossword solution for this term is 'TIDAL', which refers to the regular rise and fall of the ocean's surface due to the gravitational pull of the moon and sun.