/ Dictionary / Index F functional disease: Meaning and Definition of Find definitions for: func'tional disease" Pronunciation: [key] — Pathol. Pathol. a disease in which there is an abnormal change in the function of an organ, but no structural alteration in the tissues involved (opposed to organic disease). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. functional change functional group Related Content Daily Word Quiz: pundit Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language