/ Dictionary / Index G Gustavus III: Meaning and Definition of Find definitions for: Gustavus III Pronunciation: [key] 1746–92, king of Sweden 1771–92: economic and legal reformer. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Gustavus II Gustavus IV 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