The crossword solution for the term 'MOVE BACK AND FORTH' is 'BACK', which is a four-letter word. The phrase 'MOVE BACK AND FORTH' is an idiom that means to go BACK AND FORTH between two places or states, or to alternate between two activities. It can also be used to describe something that is constantly changing or fluctuating. This phrase is often used to describe physical movement, but it can also be used to describe mental or emotional changes.