O·sa·ka (?-sä?k?, ô?sä-kä?) A city of southern Honshu, Japan, on Osaka Bay, an inlet of the Pacific Ocean. Osaka was the leading commercial center of Japan during the feudal period and today is highly industrialized.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.Osaka (???s??k?) n (Placename) a port in S Japan, on S Honshu on Osaka Bay (an inlet of the Pacific): the third largest city in Japan (the chief commercial city during feudal times); university (1931); an industrial and commercial centre. Pop: 2 484 326 (2002 est)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014O?sa?ka (o??s? k?, ?o? s??k?) n. a city on S Honshu, in S Japan. 2,546,000. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.