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

Interestingly, some findings suggest that gray matter volume may partially recover after menopause, hinting at the brain's ability to adapt through neuroplasticity.

From Science Daily • Oct. 21, 2025

The results showed that lower pulmonary gas exchange may be associated with cognitive dysfunction, as well as lower gray matter and white matter volumes in patients with long COVID.

From Science Daily • Nov. 27, 2024

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

From Los Angeles Times • Sep. 24, 2024

The animals were, essentially, processing what just happened, allowing their tiny nuggets of gray matter to drift along and make sense of these curious humans’ images.

From Salon • Jan. 9, 2024

And the three pounds of gray matter he carried around in his skull served him well in the classroom.

From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown