/ Thesaurus / S Synonyms of sioux falls Find synonyms for: Noun1. Sioux Fallsusage: largest city in South Dakota; located in southeastern South DakotaWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language