myelin

noun

my·​e·​lin ˈmī-ə-lən 

: a soft white material that forms a thick layer around the axons of some neurons and is composed chiefly of lipids (such as cerebroside and cholesterol), water, and smaller amounts of protein

myelinic

ˌmī-ə-ˈli-nik 

adjective

Examples of myelin in a Sentence

Recent Examples on the Web

How the Brain Uses Myelin The human brain contains myelin, a fatty substance that protects neurons. —Monica Cull, Discover Magazine, 3 Apr. 2025

The progressive disease damages the protective cover around nerves called myelin in your central nervous system, according to the Cleveland Clinic. —Cara Lynn Shultz, People.com, 5 May 2025

This reversible reduction in MWF upon prolonged exercise and recovery after lowering physical activity strongly suggests changes in myelin structure and content that may open up a new view of myelin as an energy store ready to use when common brain nutrients are in short supply. —New Atlas, 25 Mar. 2025

The researchers evaluated the association of B12 concentrations with cognitive performance and myelin integrity. —New Atlas, 19 Feb. 2025

Word History

Etymology

borrowed from German Myelin, from Greek myelós "bone marrow" + German -in -in entry 1 — more at myelo-

Note: The term was introduced by Rudolf virchow in "Ueber das ausgebreitete Vorkommen einer dem Nervenmark analogen Substanz in den thierischen Geweben," Archiv für pathologische Anatomie und Physiologie und für klinische Medicin, 6. Band (1854), p. 571

First Known Use

1866, in the meaning defined above

Phrases Containing myelin

• myelin sheath

Rhymes for myelin

• sphingomyelin

Kids Definition

myelin

noun

my·​elin

ˈmī-ə-lən

: a soft white somewhat fatty material that forms a thick layer around the axons of some neurons

Medical Definition

myelin

noun

my·​e·​lin ˈmī-ə-lən 

: a soft white material of lipid and protein that is secreted by oligodendrocytes and Schwann cells and forms a thick sheath about axons see myelin sheath

myelinic

ˌmī-ə-ˈlin-ik 

adjective