/ Thesaurus / B Synonyms of brown rat Find synonyms for: Noun1. brown rat, Norway rat, Rattus norvegicus, ratusage: common domestic rat; serious pest worldwideWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: sequester Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language