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

Examples of cortex in a Sentence

Recent Examples on the Web

By contrast, implanted electrodes can be placed right next to the motor cortex and can eavesdrop on the activity of only those neurons. —Dana MacKenzie, Smithsonian Magazine, 23 Oct. 2024

Barnett’s group was able to examine the entire brain, including the parietal cortex, the region that’s considered the hub for processing numbers. —Quanta Magazine, 18 Oct. 2024

Even people without a history of mental health issues can experience executive dysfunction in daily life if certain brain areas, like the orbitofrontal cortex (OFC), are impaired or show structural differences, as mentioned in a 2012 study published in Brain Structure and Function. —Mark Travers, Forbes, 11 Oct. 2024

Strikingly, the insular cortex, a part of the brain that connects deeper brain regions with the cortex, had consistent and unique patterns for both positive and negative emotions, but not for mixed ones. —Anthony Gianni Vaccaro, The Conversation, 23 Sep. 2024

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

• cerebral cortex
• piriform cortex
• prefrontal cortex
• pyriform 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