cortex

noun ! Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about cortex at Wordnik → Where our words come from →

1. The outer layer of an internal organ or body structure, such as the kidney or the brain.
2. The tissue of a stem or root that lies inward from the epidermis, but exterior to the vascular tissue.
3. The outer surface of a piece of flint.