/ Thesaurus / S Synonyms of sioux city Find synonyms for: Noun1. Sioux Cityusage: a city in northeastern Iowa where the Big Sioux River joins the MissouriWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: denizen Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language