/ Dictionary / Index M medullation: Meaning and Definition of Find definitions for: med•ul•la•tion Pronunciation: (med"l-ā'shun, mej"u-lā'-), [key] — n. Biol. the formation of a medullary sheath about a nerve fiber. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. medullated medusa Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language