Cortex

Part of speech: noun

Pronunciation: /ˈkɔɹtɛks/

Definitions

1. The outer layer of an organ or structure, especially the folded surface of the brain responsible for higher mental functions
2. The outer region of an organ or anatomical structure that performs specialized functions distinct from its inner core
3. The outermost layer of the brain involved in complex processes like thought and memory ; the external surface of an organ distinct in function from its inner parts

Etymology: The Latin "cortex" originally meant bark, the tough outer covering of a tree, and also cork. That physical sense is the key to the anatomical one: English borrowed the word from Latin in its literal meaning, and only later was it applied to the outer layer of other things, including the brain and organs. Its roots reach back to a prehistoric Indo-European base, reconstructed as "*(s)ker-", which conveyed the idea of cutting or peeling, an apt origin for something stripped from a trunk. The Latin word carried that sense of a protective outer skin. Anatomists then extended the term to other outer layers. The cerebral cortex is the wrinkled grey matter wrapping the brain, and the same term is used for the outer zone of organs such as the kidney, where it sits apart from the inner medulla.

Synonyms: bark, covering

Antonyms: medulla