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

Studies show that the adolescent brain is significantly different than an adult brain in that the frontal cortex is still developing. Carolyn Twersky, Seventeen, "Are Teenagers Having As Much Sex as "Riverdale" Thinks They Are?," 16 May 2019 In contrast, the elephant brain, which is three times the size of our own, has 251 billion neurons in its cerebellum, which helps manage a giant, versatile trunk, and only 5.6 billion in its cortex. Quanta Magazine, "How Humans Evolved Supersize Brains," 10 Nov. 2015 In 2003, Indiana University biophysicist John Beggs and several colleagues were the first to demonstrate that slices of a brain's cortex showed evidence of an exponent relation. Jennifer Ouellette, Ars Technica, "Rat brains provide even more evidence our brains operate near tipping point," 7 June 2019 Together, the two studies suggest that the cortex both folds and unfolds differently in autism. Rachel Zamzow, Scientific American, "Brains of Children with Autism Show Unusual Folding Patterns," 9 July 2018 In living animals, the cortex’s surface layers are typically much more accessible than deep regions like the pons. Daniela Hernandez, WSJ, "The Quest to Decode the Brain," 15 June 2018 Muotri and her research team had been trying to coax human stem cells to re-create tissue found in the brain's cortex, which is devoted to cognition and interpreting sensory information. David Grossman, Popular Mechanics, "Scientists Re-create Baby Brain Readings in a Dish," 19 Nov. 2018 The researchers focused their efforts on the prefrontal cortex, temporal cortex, and cerebellum, as these regions have been implicated in susceptibility to ASD. Diana Gitig, Ars Technica, "Autism involves a large-scale reduction in RNA editing," 21 Dec. 2018 Another is the posterior cingulate cortex, which Vago says is thought to play a critical role in self-reflection and rumination. Carolyn L. Todd, SELF, "What Meditation Can—and Can’t—Do for Your Health," 11 Sep. 2018

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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Last Updated

12 Jul 2019

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The first known use of cortex was in 1677

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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 cortices (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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Rhyming Dictionary: Words that rhyme with cortex

Spanish Central: Translation of cortex

Nglish: Translation of cortex for Spanish Speakers

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

Comments on cortex

What made you want to look up cortex? Please tell us where you read or heard it (including the quote, if possible).


appealing forcibly to the mind or reason

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