D defs.my
Entry 1 sense Webster, 1913

myelin

/mī'-ĭl-ĭn/ · my·e·lin · IPA /ˈmaɪəlɪn/
01 n. A soft white substance constituting the medullary sheaths of nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin, protein,…
  1. 1.
    A soft white substance constituting the medullary sheaths of nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin, protein, and some fat.(Physiol. Chem.)