Money stack is a term used to describe a large amount of money that is organized in a neat PILE. It is often used to refer to a large sum of money that has been saved or earned over a period of time. Money stacks are also sometimes used to refer to a large amount of money that is being used to purchase something, such as a house or car. The term money stack can also be used to describe a large amount of money that is being used to invest in stocks or other financial instruments. The crossword solution for the term money stack is 'PILE, ' which is a four-letter word that describes a large amount of money that is organized in a neat PILE.