cortex

American  

[kawr-teks] / ˈkɔr tɛks /

noun

plural

cortices

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

Planning is for weaklings, rational analysis is disdained, the amygdala and the gut replace the cerebral cortex.

From Salon • Mar. 14, 2026

Levels of cholesterol and glycogen varied across regions, with the most dramatic contrasts appearing in areas responsible for memory, particularly the hippocampus and cortex.

From Science Daily • Mar. 1, 2026

Even before I first saw the film during last year’s Sundance Film Festival, this one-line elevator pitch was taking up all the space in my prefrontal cortex.

From Salon • Feb. 18, 2026

This reduced response appeared in the auditory cortex, the region responsible for processing sound and speech.

From Science Daily • Jan. 23, 2026

And finally, on the outside, living in uneasy truce with the more primitive brains beneath, is the cerebral cortex, which evolved millions of years ago in our primate ancestors.

From "Cosmos" by Carl Sagan