/ Thesaurus / R Synonyms of rock island Find synonyms for: Noun1. Rock Islandusage: a town in northwest Illinois on the Mississippi River; site of a Union prison during the American Civil WarWordNet 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