cortex

noun

cor·​tex ˈkȯr-ˌteks 

plural cortices ˈkȯr-tə-ˌsēz  also cortexes

1

a(1)

: the outer or superficial part of an organ or bodily structure (such as the kidney, adrenal gland, or cerebellum or a bone)

especially : cerebral cortex

(2)

: the proteinaceous usually pigmented layer of a hair below the cuticle

b

: the outer part of some organisms (such as paramecia)

2

: a plant bark or rind (such as cinchona) used medicinally

3

a

: the typically parenchymatous layer of tissue external to the vascular tissue and internal to the corky or epidermal tissues of a green plant

broadly : all tissues external to the xylem

b

: an outer or investing layer of various algae, lichens, or fungi

Example Sentences

Recent Examples on the Web

Within the brain’s frontal lobe lies the primary motor cortex, a sliver of neurons that coordinates movement. —Will Sullivan, Smithsonian Magazine, 21 Apr. 2023

Connections between the sensorimotor putamen and the anterior cingulate cortex, which is involved in emotion regulation, among other things, and is also implicated in habit learning, were weaker. —Byclaudia Lopez Lloreda, science.org, 29 Mar. 2023

For that typing-by-brain function, an implant is typically placed in the motor cortex, the part of the brain that controls movement. —IEEE Spectrum, 29 Oct. 2022

But the current configuration of the Neuralink device, which has electrodes implanted close to the surface of the outer layer of the brain, known as the cortex, is not set up to conduct deep brain stimulation. —Jonathan Vanian, Fortune, 7 July 2022

Some examples of physical and chemical trauma include: Heat styling: Heat can temporarily break bonds in the cortex of the hair shaft and as an unwanted side effect, the hair cuticle, which is the outer protective layer, gets damaged. —Sydney Wingfield, Women's Health, 6 Apr. 2023

When researchers used a similar light-sensitive protein to block nerve signals from the insular cortex, the mice began to explore the open arm of the maze, suggesting a calmer mental state, even though their heart rate was still skyrocketing. —Byclaudia Lopez Lloreda, science.org, 1 Mar. 2023

Keranique’s keratin amino complex reaches the cortex of the hair while strengthening the hair’s surface. —Tatjana Freund, ELLE, 13 Jan. 2023

Neuroscientists say empathic concern is supported by several regions of the brain associated with social attachment and caregiving — the ventral tegmental area, caudate nucleus and subgenual anterior cingulate cortex. —Emilie Le Beau Lucchesi, Discover Magazine, 20 May 2022

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Word History

Etymology

Latin cortic-, cortex bark — more at cuirass

First Known Use

circa 1676, in the meaning defined at sense 1a(1)

Phrases Containing cortex

• piriform cortex
• prefrontal cortex
• pyriform cortex
• cerebral cortex
• visual cortex

• piriform cortex
• prefrontal cortex
• pyriform cortex
• cerebral cortex
• visual cortex

Kids Definition

cortex

noun

cor·​tex ˈkȯr-ˌteks 

plural cortices ˈkȯrt-ə-ˌsēz  or cortexes

1

: an outer or surrounding layer of an organ or body part

the cortex of the kidney

especially : the outer layer of gray matter of the cerebrum

2

: the layer of tissue outside the xylem and phloem and inside the corky or epidermal tissues of a vascular plant

also : all tissues external to the xylem

Medical Definition

cortex

noun

cor·​tex ˈkȯr-ˌteks 

plural cortices ˈkȯrt-ə-ˌsēz  also cortexes

1

a

: the outer or superficial part of an organ or body structure (as the kidney, adrenal gland, or a hair)

especially : cerebral cortex

b

: the outer part of some organisms (as paramecia)

2

a

: a plant bark or rind (as cinchona) used medicinally

b

: the peel of any of several fruits

—used especially in the writing of medical prescriptions