/ Thesaurus / G Synonyms of gustavus iii Find synonyms for: Noun1. Gustavus, Gustavus IIIusage: king of Sweden who increased the royal power and waged an unpopular war against Russia (1746-1792)WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: foliage Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language