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.

---

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

---

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]

---

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

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

Some evidence suggests a partial recovery of gray matter volume postmenopause, potentially reflecting compensatory neuroplastic processes.

From Science Daily ● Oct. 21, 2025

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

From Los Angeles Times ● Sep. 24, 2024

Could the MRI gray matter biomarker be used widely someday?

From Science Daily ● Jan. 22, 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