cortex
noun
cor·tex
ˈkȯr-ˌteks 
plural cortices
ˈkȯr-tə-ˌsēz
also cortexes
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
Water penetrating the cortex swells the hair and weakens it.
—
Marie Bladt, Vogue, 28 Feb. 2025
That’s why the most common locations for stress reactions are in the bones of the feet, such as the calcaneus, fifth metatarsal, sesamoid, talar neck and tarsal navicular, and in the bones of the legs, such as the anterior tibial cortex, femoral neck and femoral head.
—Bruce Y. Lee, Forbes, 28 Feb. 2025
At the same time, activity decreases in a brain region known as the frontal cortex, which is responsible for judgment and logical thinking.
—Jennifer Borresen, USA TODAY, 14 Feb. 2025
Brain tissue samples were gathered from the frontal cortex, the area of the brain associated with thinking and reasoning.
—Sandee Lamotte, CNN, 3 Feb. 2025
See All Example Sentences for cortex
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Marie Bladt, Vogue, 28 Feb. 2025
That’s why the most common locations for stress reactions are in the bones of the feet, such as the calcaneus, fifth metatarsal, sesamoid, talar neck and tarsal navicular, and in the bones of the legs, such as the anterior tibial cortex, femoral neck and femoral head.
—Bruce Y. Lee, Forbes, 28 Feb. 2025
At the same time, activity decreases in a brain region known as the frontal cortex, which is responsible for judgment and logical thinking.
—Jennifer Borresen, USA TODAY, 14 Feb. 2025
Brain tissue samples were gathered from the frontal cortex, the area of the brain associated with thinking and reasoning.
—Sandee Lamotte, CNN, 3 Feb. 2025
See All Example Sentences for cortex
Cite this Entry
“Cortex.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cortex. Accessed 6 Mar. 2025.
Copy CitationKids Definition
cortex
noun
cor·tex
ˈkȯr-ˌteks
plural cortices
ˈkȯrt-ə-ˌsēz
or cortexes
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
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
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