white matter

American  

noun

Anatomy.

1. nerve tissue, especially of the brain and spinal cord, which primarily contains myelinated fibers and is nearly white in color.

---

white matter British  

noun

1. Technical name: substantia alba.  the whitish tissue of the brain and spinal cord, consisting mainly of myelinated nerve fibres Compare grey matter

---

white matter Scientific  

1. The whitish tissue of the vertebrate brain and spinal cord, made up chiefly of nerve fibers (axons) covered in myelin sheaths.

2. Compare gray matter

---

Etymology

Origin of white matter

First recorded in 1830–40

Compare meaning

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

• gray matter vs. white matter

Example Sentences

Surrounding that is white matter, made up of astrocytes and long nerve fibers that carry signals between the brain and the rest of the body.

From Science Daily • Feb. 13, 2026

The research focuses on how networks of white matter connections allow different brain regions to communicate, supporting thinking, decision making, and behavior.

From Science Daily • Jan. 3, 2026

The researchers also looked at white matter damage, a widely used indicator of Alzheimer's, and found it was associated with six of the seven blood markers.

From Science Daily • Jan. 3, 2026

The scans helped show white matter, the fatty substance that insulates the nerve fibers connecting brain regions.

From The Wall Street Journal • Dec. 23, 2025

The spinal cord consists of an outer portion, mainly of nervous fibres, the white matter, and of inner, ganglionated, and more highly vascular grey matter.

From Text Book of Biology, Part 1: Vertebrata by Wells, H. G. (Herbert George)