Botany. a narrow zone made up of the innermost layer of woody tissue immediately surrounding the pith in plants.
Anatomy. myelin sheath.
These Plain Words Have Very Odd Origin StoriesOver the years, these words have gone on a journey from signifying creepy, strange, antithetical, and even paranormal ideas to taking on the standard meanings we know and understand today.
- medullary groove,
- medullary membrane,
- medullary plate,
- medullary pyramid,
- medullary ray,
- medullary space,
- medullary sponge kidney,
- medullary stria of fourth ventricle,
- medullary stria of thalamus,
- medullary substance
Origin of medullary sheath
First recorded in 1840–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
anatomy a myelin layer surrounding and insulating certain nerve fibres
a layer of thick-walled cells surrounding the pith of the stems of some higher plants
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
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.