The term 'FILLS PARTS' can be solved by the word 'CASTS', which is a five-letter word. The term 'casts' is used to describe the process of creating a replica of an object, usually in metal or plastic. This process is often used in the production of films and plays, where actors are cast in certain roles. It can also be used in the production of sculptures, where a mold is created from a model and then filled with a material such as plaster or clay. In both cases, the casts are used to create a replica of the original object.