/ Dictionary / Index M myoblast: Meaning and Definition of Find definitions for: my•o•blast Pronunciation: (mī'u-blast"), [key] — n. Embryol. any of the cells derived from the mesoderm in the vertebrate embryo that develop into muscle tissue. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. M.Y.O.B. myocardial infarction 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