cortex

noun (plural cortices /-tɪˌsiːz/)

• 1 Anatomy the outer layer of the cerebrum (the cerebral cortex), composed of folded grey 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.

• 2 Botany an outer layer of tissue immediately below the epidermis of a stem or root.