/ Thesaurus / R Synonyms of river styx Find synonyms for: Noun1. Styx, River Styxusage: (Greek mythology) a river in Hades across which Charon carried dead soulsWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language