I·sère (?-zâr?) A river, about 290 km (180 mi) long, of southeast France rising in the Graian Alps near the Italian border and flowing west and southwest to the Rhone River.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.Isère (French iz?r) n1. (Placename) a department of SE France, in Rhône-Alpes region. Capital: Grenoble. Pop: 1 128 755 (2003 est). Area: 7904 sq km (3083 sq miles)2. (Placename) a river in SE France, rising in the Graian Alps and flowing west and southwest to join the River Rhône near Valence. Length: 290 km (180 miles)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014I?sère (i?z??r) n. a river in SE France, flowing from the Alps to the Rhone River. 150 mi. (240 km) long. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.