Ceph·a·lo·ni·a (s?f??-l??n?-?, -l?n?y?) also Ke·fal·li·ní·a (k??fä-l?-n??ä) The largest of the Ionian Islands off the western coast of Greece. It was held by the British from 1809 to 1864.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.Cephalonia (?s?f??l??n??) or Kefallonian (Placename) a mountainous island in the Ionian Sea, the largest of the Ionian Islands, off the W coast of Greece. Pop: 36 404 (2001). Area: 935 sq km (365 sq miles). Modern Greek name: Kephallinía Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Ceph?a?lo?ni?a (?s?f ??lo? ni ?, -?lo?n y?) n. the largest of the Ionian Islands, off the W coast of Greece. 31,297; 287 sq. mi. (743 sq. km). Greek, Kefallinia. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.