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

Nature also developed myelin, the fatty sheath around nerve fibers that allows electrical signals to travel up to 100 times faster than through unmyelinated neurons. — Bratin Saha, Forbes.com, 21 Aug. 2026

The chemicals may also harm cells in the brain and spinal cord that create myelin, according to a 2024 study in human tissue. — Sandee Lamotte, CNN Money, 7 Aug. 2026

Neurochemistry is the study of all of the chemicals in the nervous system, but particularly for immunologists, the chemistry of myelin. — Marcy Thompson, Scientific American, 16 Apr. 2026

Without myelin, signals that would normally rapidly fire across nerves are slowed or blocked. — Kaitlin Sullivan, NBC news, 15 Mar. 2026

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