What does cranium mean?
The cranium is the bony structure of the head that encloses and protects the brain, forming the upper portion of the skull above the facial bones. In humans it consists of eight bones joined by immovable joints known as sutures, an arrangement that gives the adult head rigidity while allowing the infant skull to remain slightly flexible. The word belongs mainly to formal and technical contexts — anatomy, medicine, forensic science — where precision matters more than in casual speech, which favors 'skull'. Writers might describe a fracture to the cranium after an accident or note how a helmet shields it from impact. Its plural is either 'craniums' or, especially in scientific usage, 'crania'. Related forms such as 'cranial' appear frequently in medical vocabulary, as in cranial nerves or cranial surgery.
nounThe bony structure that encloses and protects the brain; the upper part of the skull.
- The bony case enclosing the brain; the part of the skull above the face.
"The scan revealed a small fracture along the left side of his cranium."
"A helmet absorbs impact before it reaches the cranium."
"In anatomy class we learned that the cranium consists of eight fused bones."
'Craniа' follows the Latin plural and is favored in scientific contexts; 'craniums' is fully acceptable in general use.
"The museum's comparative collection displays the crania of several hominin species."
Your cranium isn't one bone but eight, knitted together at joints called sutures — which is why a baby's skull can still flex during birth.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cranium
Cranium derives from the Greek 'kranion', meaning skull or head, which passed into Medieval Latin and entered English in the early modern period, by the mid-15th century according to some sources. It is related to the Greek 'kara', also meaning head, both ultimately tracing back to a Proto-Indo-European root associated with the head or horns. The adjective 'cranial' developed later within anatomical terminology.
Related word forms
How cranium is actually used
Formal and technical register, used chiefly in anatomy and medicine; 'skull' is the everyday equivalent. The plural is 'craniums' or the Latinate 'crania', with the latter preferred in scientific writing.
Easily confused with cranium
The cerebrum is part of the brain itself, whereas the cranium is the bone surrounding it.
The skull includes the facial bones as well as the jaw, while the cranium refers specifically to the brain-enclosing portion.