n. pl. me·dul·las or me·dul·lae (-dŭlē)
1. The inner core of certain organs or body structures, such as the marrow of bone.
2. The medulla oblongata.
3. See myelin.
a. The pith in the stems or roots of certain plants.
b. The central portion of a thallus in certain lichens and red or brown algae.
[Middle English, from Latin, perhaps alteration (influenced by medius, middle) of *merulla.]
me·dullar, medul·lar′y (mĕdl-ĕr′ē, mə-dŭlə-rē) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.