Sinn Fein (sh?n f?n?, f???n)n. 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.[Irish Gaelic sinn féin : sinn, we (from Middle Irish, from Old Irish) + féin, self (from Middle Irish, from Old Irish; see s(w)e- in Indo-European roots).]Sinn Fein?er n.Sinn? Fein?ism n.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Sinn Féin (???n ?fe?n) n (Government, Politics & Diplomacy) an Irish republican political movement founded about 1905 and linked to the revolutionary Irish Republican Army: divided into a Provisional and an Official movement since a similar split in the IRA in late 1969[C20: from Irish: we ourselves] Sinn Féiner n Sinn Féinism nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Sinn Fein (???n ?fe?n) n. an Irish nationalist organization founded about 1905, existing today as the political wing of the Irish Republican Army. [