/ Dictionary / Index D Department of the Interior: Meaning and Definition of Find definitions for: Depart'ment of the Inte'rior Pronunciation: [key] the department of the U.S. federal government charged with the conservation and development of the natural resources of the U.S. and its possessions. Abbr.: DOI Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Department of State Department of the Treasury Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language