an Irish nationalist organization and political party formed in 1905: the present-day organization is regarded as the political wing of the Irish Republican Army
See Sinn Fein in American Heritage Dictionary 4
(shĭn fānˈ, fĕˈĭn)
noun
An Irish political and cultural society founded about 1905 to promote political and economic independence from England, unification of Ireland, and a renewal of Irish culture. It now constitutes the political branch of the Irish Republican Army.