/ Dictionary / Index S S.D.A.: Meaning and Definition of Find definitions for: S.D.A. Pronunciation: [key] Seventh Day Adventists. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. SD S. Dak. Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language