cor·​tex | \ ˈkȯr-ˌteks How to pronounce cortex (audio) \
plural cortices\ ˈkȯr-​tə-​ˌsēz How to pronounce cortex (audio) \ or cortexes

Definition of cortex

1a(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
3a : 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 The tension between accuracy and identity probably involves a brain region called the orbitofrontal cortex, which computes the value of goals and beliefs and is strongly connected to memory, executive function and attention. Lydia Denworth, Scientific American, "Conservative and Liberal Brains Might Have Some Real Differences," 26 Oct. 2020 But as our heart rate speeds up and our breathing becomes shallower, a well-functioning frontal cortex will then take a minute to decide what that response should be — fight or flight, escalate or de-escalate. Mary Mcnamara Culture Columnist And Critic, Los Angeles Times, "Column: How do I detox from a four-year Twitter-fed outrage addiction? One Trump-free day at a time," 11 Nov. 2020 In a human child, on the other hand, there are a massive number of neurons that form and populate the cortex after birth. Priyanka Runwal, STAT, "New screening technique turns up genes tied to microcephaly, scientists say, and could be used for other developmental disorders," 30 Oct. 2020 In combination with smart spectral processing of the signals those electrodes pick up, ECoG is good enough to translate action in the part of the motor cortex that controls the lips, jaw, and tongue into text or even speech. Adam Rogers, Wired, "A New Way to Plug a Human Brain into a Computer: via Veins," 29 Oct. 2020 The team tested their model by verifying its predictions about activity in the inferior temporal cortex of rhesus macaques. Quanta Magazine, "Deep Neural Networks Help to Explain Living Brains," 28 Oct. 2020 The mammalian cortex is organized into six layers containing vertical columns of neurons that communicate with one another both horizontally and vertically. Bret Stetka, Scientific American, "Bird Brains Are Far More Humanlike Than Once Thought," 24 Sep. 2020 By contrast, the neurons in the neighboring medial entorhinal cortex—which the team’s leaders previously studied in relation to space—fired predictably. Doug Johnson, National Geographic, "How you perceive time may depend on your income," 22 Sep. 2020 The device’s electrodes were situated in a part of Gertrude’s cortex that connected to neurons in her snout. Tanya Lewis, Scientific American, "Elon Musk’s Pig-Brain Implant Is Still a Long Way from ‘Solving Paralysis’," 2 Sep. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cortex.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of cortex

1677, in the meaning defined at sense 1a(1)

History and Etymology for cortex

Latin cortic-, cortex bark — more at cuirass

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Time Traveler for cortex

Time Traveler

The first known use of cortex was in 1677

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Last Updated

18 Dec 2020

Cite this Entry

“Cortex.” Dictionary, Merriam-Webster, Accessed 15 Jan. 2021.

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How to pronounce cortex (audio)

English Language Learners Definition of cortex

medical : the outer layer of an organ in the body and especially of the brain


cor·​tex | \ ˈkȯr-ˌteks How to pronounce cortex (audio) \
plural cortices\ ˈkȯrt-​ə-​ˌsēz How to pronounce cortex (audio) \ or cortexes

Medical Definition of cortex

1a : 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)
2a : 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

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More from Merriam-Webster on cortex

Nglish: Translation of cortex for Spanish Speakers

Britannica English: Translation of cortex for Arabic Speakers Encyclopedia article about cortex

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