gray matter

American  

noun

1. Anatomy. nerve tissue, especially of the brain and spinal cord, that contains fibers and nerve cell bodies and is dark reddish-gray.

2. Informal. brains or intellect.

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gray matter Scientific  

1. The brownish-gray tissue of the vertebrate brain and spinal cord, made up chiefly of the cell bodies and dendrites of neurons.

2. Compare white matter

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gray matter Idioms  

1. Brains, intellect, as in If you'd only use your gray matter, you'd see the answer in a minute. This expression refers to actual brain tissue that is gray in color. Agatha Christie's fictional detective, Hercule Poirot, constantly alludes to using the little gray cells for solving a crime. [Late 1800s]

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Etymology

Origin of gray matter

First recorded in 1830–40

Compare meaning

How does gray-matter compare to similar and commonly confused words? Explore the most common comparisons:

• gray matter vs. white matter

Example Sentences

See Examples For:

gray matter

Using the MRI scans, they measured the volume of gray matter and white matter in each participant's brain while accounting for differences in overall brain size.

From Science Daily ● Jul. 1, 2026

Participants who stopped practicing music showed declines in verbal working memory and a reduction in gray matter volume within the right putamen.

From Science Daily ● Jun. 13, 2026

Both were strongly associated with gray matter loss, faster brain aging, cognitive decline, and a higher risk of neurological disease.

From Science Daily ● Jan. 28, 2026

AFM attacks motor neurons in the spinal cord’s gray matter, which controls movement.

From Los Angeles Times ● Sep. 24, 2024

It took my altitude-impaired gray matter a minute or two to comprehend that the object was a human body.

From "Into Thin Air" by Jon Krakauer