/ Thesaurus / R Synonyms of river boulder Find synonyms for: Noun1. river boulder, boulder, bowlderusage: a boulder that has been carried by a river to a place remote from its place of originWordNet 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