/ Dictionary / Index A ascus: Meaning and Definition of Find definitions for: as•cus Pronunciation: (as'kus), [key] — pl. as•ci the sac in ascomycetes in which the sexual spores are formed. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: ascus (Thesaurus) ASCU asdic Related Content Daily Word Quiz: alacrity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language