from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A white fatty material, composed chiefly of lipids and lipoproteins, that encloses certain axons and nerve fibers. Also called medulla.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A white, fatty material, composed of lipids and lipoproteins, that surrounds the axons of nerves.
from the GNU version of the Collaborative International Dictionary of English
- n. A soft white substance constituting the medullary sheaths of nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin, protein, and some fat.
- n. One of a group of phosphorized principles occurring in nerve tissue, both in the brain and nerve fibers.
from The Century Dictionary and Cyclopedia
- n. In anatomy, the white substance of Schwann, or medullary sheath of a nerve.
- Resembling myelin: said of lecithin which has been placed in water and has become swollen and pasty. On microscopical examination it will then be seen to exist in the form of peculiar slimy droplets and threads, which are known as the myelin forms of the substance.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers
From Ancient Greek μυελός (myelos, "marrow") + -in (Wiktionary)