/ Dictionary / Index P phenylketonuria: Meaning and Definition of Find definitions for: phen•yl•ke•to•nu•ri•a Pronunciation: (fen"l-kē"tō-noor'ē-u, -nyoor'-, fēn"-), [key] — n. Pathol. an inherited disease due to faulty metabolism of phenylalanine, characterized by phenylketones in the urine and usually first noted by signs of mental retardation in infancy. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: phenylketonuria (Thesaurus) phenyl isocyanate phenylmethane Related Content Daily Word Quiz: miscreant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language