The crossword solution for the term HEAP (ON) is LOAD. This is a four letter word that is used to describe the act of putting a large amount of something in one place. It can also be used to refer to the amount of something that has been put in one place. The term is often used in relation to physical objects, such as a pile of wood or a stack of books, but it can also be used figuratively to refer to a large amount of something, such as a heap of problems or a LOAD of work.