/ Dictionary / Index M megakaryocyte: Meaning and Definition of Find definitions for: meg•a•kar•y•o•cyte Pronunciation: (meg"u-kar'ē-u-sīt"), [key] — n. Cell Biol. a large bone-marrow cell having a lobulate nucleus, regarded as the source of blood platelets. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: megakaryocyte (Thesaurus) megakaryoblast megal- Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language