/ Dictionary / Index D diagnosticate: Meaning and Definition of Find definitions for: di•ag•nos•ti•cate Pronunciation: (dī"ug-nos'ti-kāt"), [key] — -cat•ed, -cat•ing. to diagnose. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. diagnostic diagnostician Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language