Skullcap

Noun

1. A small domed cap that covers the area from the forehead to just above the back of the neck.
2. A yarmulke-like hat.
3. The calvaria, the top part of the skull, covering the cranial cavity containing the brain.
4. Any of several species of flowering plants of the genus Scutellaria, in the Lamiaceae family.
5. A torture device for compressing the skull.