/ Thesaurus / R Synonyms of red river Find synonyms for: Noun1. Red, Red Riverusage: a tributary of the Mississippi River that flows eastward from Texas along the southern boundary of Oklahoma and through LouisianaWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language