The term 'PART OF A BED' can be solved by the 8-letter word 'MATTRESS'. A MATTRESS is a large, rectangular piece of furniture that is placed on top of a bed frame and is used as a sleeping surface. It is usually filled with materials such as foam, latex, or springs to provide cushioning and support for the body. Mattresses come in a variety of sizes, shapes, and materials, and are often covered with a sheet or blanket for comfort.