The jaw bone, or MANDIBLE, is an 8-letter term that refers to the lower jawbone. It is the only movable bone in the skull and is connected to the temporal bones at the sides of the head. The MAXILLA is a 7-letter term that refers to the upper jawbone. It is composed of two fused bones and forms the upper jaw, as well as the roof of the mouth. Together, the MANDIBLE and MAXILLA form the jaw bone, which is essential for chewing and speaking.