/ Thesaurus / R Synonyms of rain barrel Find synonyms for: Noun1. rain barrel, cisternusage: a barrel used as a cistern to hold rainwaterWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language