Cranial means relating to the skull, the hard bony structure that protects your brain. Doctors and scientists use this word when they're talking about anything connected to the skull or the head region.

When you hear about cranial nerves, those are the twelve pairs of nerves that connect directly to your brain, controlling things like your sense of smell, your eye movements, and your ability to taste food. A cranial injury means damage to the head or skull. Doctors might order a cranial scan to look at images of someone's brain and skull to check for problems.

You might encounter this word in science class when studying the human skeleton, or in a hospital setting where doctors need precise language to describe different parts of the body. While “skull” and “cranium” mean roughly the same thing, cranial is the adjective form that medical professionals prefer when describing anything skull-related, from cranial bones to cranial capacity (how much space is inside the skull).