/ Dictionary / Index H hydronephrosis: Meaning and Definition of Find definitions for: hy•dro•ne•phro•sis Pronunciation: (hī"drō-nu-frō'sis), [key] — n. Pathol. dilation of the branches and pelvic cavity of the kidney, caused by an accumulation of urine resulting from obstruction of normal outflow. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: hydronephrosis (Thesaurus) hydronaut hydronic Related Content Daily Word Quiz: aversion Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language