Bark, as of a tree; hence, an outer covering.
- Anatomy The outer layer of an internal organ or body structure, as of the kidney or adrenal gland.
- Anatomy The outer layer of gray matter that covers the surface of the cerebral hemisphere.
- Botany The region of tissue in a root or stem lying between the epidermis and the vascular tissue.
- An external layer, such as bark or rind.