/ Thesaurus / S Synonyms of sinn fein Find synonyms for: Noun1. Sinn Fein, political movementusage: an Irish republican political movement founded in 1905 to promote independence from England and unification of Ireland; became the political branch of the Irish Republican ArmyWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: loathe Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language