Oklahoma City The capital and largest city of Oklahoma, in the central part of the state. It was settled during the land rush of April 1889 and became the capital in 1910.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.Oklahoma City n (Placename) a city in central Oklahoma: the state capital and a major agricultural and industrial centre. Pop: 523 303 (2003 est) Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014O?klaho?ma Cit?y n. the capital of Oklahoma, in the central part. 469,852. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.