Final answer:
The root word for skull is 'cranium.' It is a term associated with the cranial cavity of the skull, which houses the brain and comprises eight bones that are fused together in adults, with the exception of the mandible.
Step-by-step explanation:
The root word for skull is cranium. This term is particularly used to refer to the part of the skull that encloses the brain, known as the cranial cavity. In the adult human, the skull is a complex structure made up of 22 bones, which include the eight cranial bones and 14 facial bones. The cranial bones consist of the frontal bone, two parietal bones, two temporal bones, occipital bone, sphenoid bone, and the ethmoid bone. All these bones are fused together with connective tissue in adulthood, making them immobile, with the exception of the mandible or lower jawbone, which remains movable.