/ Dictionary / Index U urea cycle: Meaning and Definition of Find definitions for: ure'a cy"cle Pronunciation: [key] — Biochem. Biochem. a metabolic process by which ammonia derived from amino acids is converted into urea in the liver. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. urea urea-formaldehyde resin Related Content Daily Word Quiz: portent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language