The term BASE FOR A MONUMENT can be summarized by two crossword solutions: PLINTH (6 letters) and plith (5 letters). A PLINTH is a base or platform that supports a structure, such as a monument. It is usually made of stone, concrete, or brick. A plith is a flat stone slab used as a base for a monument or other structure. It is often used in the construction of walls, columns, and other architectural features.