/ Dictionary / Index U ultrastructure: Meaning and Definition of Find definitions for: ul•tra•struc•ture Pronunciation: (ul'tru-struk"chur), [key] — n. Cell Biol. the structures of a cell that are revealed by electron microscopy. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ultrasound Ultrasuede Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language