Anatomy. nerve tissue, especially of the brain and spinal cord, that contains fibers and nerve cell bodies and is dark reddish-gray.Compare white matter.
Informal. brains or intellect.
Origin of gray matter
First recorded in 1830–40
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Brownish-gray nerve tissue, especially of the brain and spinal cord, composed of nerve cell bodies and their dendrites and some supportive tissue.gray substance substantia grisea
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
The brownish-gray tissue of the vertebrate brain and spinal cord, made up chiefly of the cell bodies and dendrites of neurons. Compare white matter.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Idioms and Phrases with gray matter
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]
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.