cortex

1. (countable, anatomy) The outer layer of an internal organ or body structure, such as the kidney or the brain.Examples: "In the study, led by Ryota Kanai of the University College London, people who identified themselves as liberals generally had a larger anterior cingulate cortex — a comma-shaped region near the front of the brain that is involved in decision-making. By contrast, those who identified as conservatives had larger amygdalas — almond-shaped structures that are linked with emotional learning and the processing of fear."countable

2. (uncountable, botany) The tissue of a stem or root that lies inward from the epidermis, but exterior to the vascular tissue.uncountable

3. (archaeology) The outer surface of a piece of flint.countableuncountable