/ Dictionary / Index N NDAC: Meaning and Definition of Find definitions for: NDAC Pronunciation: [key] National Defense Advisory Commission. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ND N.Dak. 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