Noun | 1. | Sinn Fein - 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 Army IRA, Irish Republican Army, Provisional IRA, Provisional Irish Republican Army, Provos - a militant organization of Irish nationalists who used terrorism and guerilla warfare in an effort to drive British forces from Northern Ireland and achieve a united independent Ireland political movement - a group of people working together to achieve a political goal |