/ Dictionary / Index B blastodisk: Meaning and Definition of Find definitions for: blas•to•disk Pronunciation: (blas'tu-disk"), [key] — n. Embryol. the blastula that forms as a flattened sphere on top of the yolk in the yolk-laden eggs of birds and reptiles. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. blastoderm blastoff Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language