/ Dictionary / Index E epiblast: Meaning and Definition of Find definitions for: ep•i•blast Pronunciation: (ep'u-blast"), [key] — n. Embryol. the primordial outer layer of a young embryo before the segregation of the germ layers, capable of becoming the ectoderm and containing cells capable of becoming the mesoderm and endoderm. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. epibiotic epiboly Related Content Daily Word Quiz: pristine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language