SQUUSH is a term used to describe the act of mashing or squishing something. It is derived from the combination of the words 'SQUISH' and 'MASH'. The term is often used in cooking, where it refers to the process of combining ingredients together to create a dish. It can also be used to describe the act of pressing down on something with force, such as when making a sandwich or pressing a button. In the crossword puzzle, the answer to the clue 'MASH' was SQUUSH.