The term FITTING TOOL can be summarized as a tool used to size or measure something. The crossword solution SIZER is a five-letter word that describes this tool. A sizer is a device used to measure the size of an object, such as clothing, jewelry, or other items. It is often used in the fashion industry to ensure that garments fit properly. It is also used in the jewelry industry to determine the size of rings and other pieces. Sizers are also used in the construction industry to measure the size of pipes, beams, and other materials.