cortex

noun (plural cortices /-təˌsēz/)

• the outer layer of the cerebrum (the cerebral cortex), composed of folded gray matter and playing an important role in consciousness.
• an outer layer of another organ or body part such as a kidney (the renal cortex), the cerebellum, or a hair.
• Botany an outer layer of tissue immediately below the epidermis of a stem or root.