/ Dictionary / Index A ascidium: Meaning and Definition of Find definitions for: as•cid•i•um Pronunciation: (u-sid'ē-um), [key] — pl. -cid•i•a a baglike or pitcherlike part. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ascidian ascigerous Related Content Daily Word Quiz: lyceum Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language