ENGLISH
REFERENCE

cortex

n.
US //ˈkɔɹtɛks// UK //kˈɔːtɛks// cor·tex
  1. 1 anatomy (n.)
    C1 Advanced Technical Medicine

    the outer layer of an organ in the body, especially the brain or the kidneys.

    the outer layer of an internal organ or body structure, such as the kidney or the brain. Often used specifically to refer to the cerebral cortex.

    Example

    The doctor explained that the outer part of the brain is called the cerebral cortex.

    Example

    Damage to the prefrontal cortex can significantly alter a person's ability to make complex decisions or regulate social behaviour.

    Usage

    The plural form is 'cortices'.
  2. 2 botany (n.)
    C2 Proficiency Technical Science

    the layer of a plant's stem or root that is just under the skin.

    the tissue of a stem or root that lies inward from the epidermis but exterior to the vascular tissue.

    Example

    In some plants, the cortex stores food like starch.

    Example

    The researchers examined the root cortex under a microscope to see how the plant absorbed water from the soil.

    Usage

    Usually uncountable in a general sense, but countable when referring to specific layers.
  3. 3 archaeology (n.)
    C2 Proficiency Technical Science

    the rough outer surface of a stone, like flint, before it is shaped into a tool.

    the outer surface or 'skin' of a piece of flint or other stone, often removed during the process of making stone tools.

    Example

    The ancient tool still had some of the white cortex on its handle.

    Example

    By analysing the remaining cortex on the flint flakes, the archaeologists determined that the raw material had been transported from a distant riverbed.
Origin

Borrowed from Latin cortex (“cork, bark”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

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Last updated June 20, 2026