cor·tex | \ ˈkȯr-ˌteks \
plural cortices\ˈkȯr-tə-ˌsēz \ 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

However, in a young child who becomes blind, as with Helen Keller, this same cortex can be repurposed for entirely distinct functions, like language processing. New York Times, "My Patient’s Smile," 16 May 2018 With Neuropixels, scientists have realized these signals are more common in the cortex than previously thought. Daniela Hernandez, WSJ, "The Quest to Decode the Brain," 15 June 2018 Independently, parrots have evolved an enlarged area that connects the cortex and the cerebellum, similar to primates. Brigit Katz, Smithsonian, "Unique Brain Circuitry Might Explain Why Parrots Are So Smart," 7 July 2018 Two thirds of the clusters detected were traveling waves moving from the rear to the front of the cortex. Simon Makin, Scientific American, "“Traveling” Brain Waves May Be Critical for Cognition," 28 June 2018 Subjects showed marked activation in the parts of the brain associated with pleasure and feeling good, in particular the orbitofrontal cortex. Linda Rodriguez Mcrobbie,, "How ice cream made America," 30 June 2018 Dr Haussler stumbled on his discovery while comparing the development of the brain’s cortex in human beings and in macaques, a type of monkey. The Economist, "A history of big-headedness," 31 May 2018 This measurement reflects both the number of folds and their depth at approximately 340,000 points across the cortex. Rachel Zamzow, Scientific American, "Brains of Children with Autism Show Unusual Folding Patterns," 9 July 2018 The occipital cortex processes visual information and allows us to see faces, trees, the stars. New York Times, "My Patient’s Smile," 16 May 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.

See More

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

Keep scrolling for more

Learn More about cortex

Statistics for cortex

Last Updated

6 Sep 2018

Look-up Popularity

Time Traveler for cortex

The first known use of cortex was in 1677

See more words from the same year

Keep scrolling for more

More Definitions for cortex



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 \
plural cortices\ˈkȯrt-ə-ˌsēz \ 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

Keep scrolling for more

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).


to deposit or conceal in a hiding place

Get Word of the Day daily email!

Test Your Vocabulary

Name that Food Quiz

True or False

Test your knowledge - and maybe learn something along the way.

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!