/ Dictionary / Index C congius: Meaning and Definition of Find definitions for: con•gi•us Pronunciation: (kon'jē-us), [key] — pl. -gi•i (in prescriptions) a gallon (3.7853 liters). an ancient Roman unit of liquid measure equal to about 0.8 U.S. gallon (3.2 liters). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: congius (Thesaurus) congestive heart failure conglobate Related Content Daily Word Quiz: agitated Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language