/ Dictionary / Index E endosteum: Meaning and Definition of Find definitions for: en•dos•te•um Pronunciation: (en-dos'tē-um), [key] — pl. -te•a the membrane lining the medullary cavity of a bone. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: endosteum (Thesaurus) endosporium endostosis Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language