/ Dictionary / Index G Gustavus I: Meaning and Definition of Find definitions for: Gustavus I Pronunciation: [key] (Gustavus Vasa) 1496–1560, king of Sweden 1523–60. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Gustavus Gustavus II Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language