/ Thesaurus / I Synonyms of internal revenue service Find synonyms for: Noun1. Internal Revenue Service, IRS, agency, federal agency, government agency, bureau, office, authorityusage: the bureau of the Treasury Department responsible for tax collectionsWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: penury Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language