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[mahy-uh-lin] /ˈmaɪ ə lɪn/
noun, Biology.
a soft, white, fatty material in the membrane of Schwann cells and certain neuroglial cells: the substance of the myelin sheath.
Also, myeline
[mahy-uh-leen] /ˈmaɪ əˌlin/ (Show IPA)
Origin of myelin
First recorded in 1865-70; myel- + -in2
Related forms
myelinic, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for myelin
Contemporary Examples
Historical Examples
  • Alveolar cells commonly contain fat-droplets and, less frequently, myelin globules.

    A Manual of Clinical Diagnosis James Campbell Todd
  • Between the neurolemma and the axis cylinder is the medullated sheath, composed of a fatty substance known as myelin.

    Manual of Surgery Alexis Thomson and Alexander Miles
British Dictionary definitions for myelin


a white tissue forming an insulating sheath (myelin sheath) around certain nerve fibres. Damage to the myelin sheath causes neurological disease, as in multiple sclerosis
Derived Forms
myelinic, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for myelin

also myeline, "soft material found in nerve tissues," 1867, from German Myelin (1854), from Greek myelos "marrow; the brain, innermost part," of unknown origin.

Online Etymology Dictionary, © 2010 Douglas Harper
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myelin in Medicine

myelin my·e·lin (mī'ə-lĭn) or my·e·line (-lĭn, -lēn')

  1. A white fatty material composed chiefly of alternating layers of lipids and lipoproteins that encloses the axons of myelinated nerve fibers.

  2. Droplets of lipid formed during autolysis and postmortem decomposition.

my'e·lin'ic adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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myelin in Science
A whitish, fatty substance that forms a sheath around many vertebrate nerve fibers. Myelin insulates the nerves and permits the rapid transmission of nerve impulses. The white matter of the brain is composed of nerve fibers covered in myelin.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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