Yours, Etc.: Origins and Uses of 8 Sign-Offs
"bony framework of the head," c.1200, probably from Old Norse skalli "a bald head, skull," a general Scandinavian word (cf. Swedish skulle, Norwegian skult), probably related to Old English scealu "husk" (see shell (n.)). But early prominence in southwestern texts suggests rather origin from a Dutch or Low German cognate (e.g. Dutch schol "turf, piece of ice," but the sense of "head bone framework" is wanting). Derivation from Old French escuelle seems unlikely on grounds of sound and sense. Old English words for skull include heafod-bolla.
The bony or cartilaginous framework of the head, made up of the bones of the braincase and face; cranium.
The part of the skeleton that forms the framework of the head, consisting of the bones of the cranium, which protect the brain, and the bones of the face. See more at skeleton.