/ Thesaurus / D Synonyms of darius i Find synonyms for: Noun1. Darius I, Darius the Greatusage: king of Persia who expanded the Persian Empire and invaded Greece but was defeated at the battle of Marathon (550-486 BC)WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: abstain Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language