cortex

American  

[kawr-teks] / ˈkɔr tɛks /

noun

cortices plural

1. Anatomy, Zoology.

   1. the outer region of an organ or structure, as the outer portion of the kidney.

   2. the cerebral cortex.

2. Botany.

   1. the portion of a stem between the epidermis and the vascular tissue; bark.

   2. any outer layer, as rind.

3. Mycology. the surface tissue layer of a fungus or lichen, composed of massed hyphal cells.

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cortex British  

/ ˈkɔːtɛks, ˈkɔːtɪkəl /

noun

1. anatomy the outer layer of any organ or part, such as the grey matter in the brain that covers the cerebrum ( cerebral cortex ) or the outer part of the kidney ( renal cortex )

2. botany

   1. the unspecialized tissue in plant stems and roots between the vascular bundles and the epidermis

   2. the outer layer of a part such as the bark of a stem

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cortex Scientific  

/ kôr′tĕks′ /

1. The outer layer of an organ or body part, such as the cerebrum or the adrenal glands.

2. The region of tissue lying between the epidermis (the outermost layer) and the vascular tissue in the roots and stems of plants. It is composed of collenchyma, parenchyma, and sclerenchyma. In roots the cortex transfers water and minerals from the epidermis to the vascular tissue, which distributes them to other parts of the plant. The cortex also provides structural support and stores food manufactured in the leaves.

3. See illustration at xylem

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Other Word Forms

• cortical
  adjective
• cortically
  adverb
• subcortex
  noun

Etymology

Origin of cortex

1650–60; < Latin: bark, rind, shell, husk

Explanation

The cortex refers to the outer layer of an organ or structure in the body, like the brain, where it plays a crucial role in processing information and thoughts. The cortex in any organ helps to protect it and make sure it functions properly. For example, the brain's cerebral cortex is crucial for high-level functions like memory, attention, thought, and consciousness. However, the term isn't exclusive to the brain; the kidney and adrenal glands also have a cortex essential to their operation. In each case, the cortex plays an important role in maintaining the organ’s overall health.

Example Sentences

Research suggests that trauma can leave the amygdala—the brain’s threat-detection center—chronically overactivated, while dampening the prefrontal cortex, which governs reasoning.

From The Wall Street Journal • May 26, 2026

The team also used pattern visual evoked potentials – a painless test that measured how well signals travelled from the retina to the visual cortex.

From BBC • Apr. 22, 2026

Changes in their activity also influenced how fear-related signals reached the prefrontal cortex, a region involved in decision-making.

From Science Daily • Apr. 4, 2026

This region connects to the prefrontal cortex, forming a thalamocortical circuit that supports decision-making and executive control.

From Science Daily • Apr. 3, 2026

Damasio studied patients with damage to a small but critical part of the brain called the ventromedial prefrontal cortex, which lies behind the nose.

From "Blink" by Malcolm Gladwell