Poi·tou (pwä-to?o?) A historical region of west-central France bordering on the Bay of Biscay. A part of the Roman province of Aquitania, it fell to the Visigoths (ad 418) and the Franks (507) and was frequently contested by France and England until the end of the Hundred Years’ War, when it was incorporated into the French crown lands.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.Poitou (French pwatu) n (Placename) a former province of W central France, on the Atlantic. Chief town: PoitiersCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Poi?tou (pwa?tu) n. a region and former province in W France. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.