Mer·ci·a (mûr?sh?-?, -sh?) An Anglo-Saxon kingdom of central England. It was settled by Angles c. ad 500 and enjoyed its greatest influence during the rule (757-796) of Offa. In 874 the kingdom was overrun by the Danes and split between Wessex and the Danelaw.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.Mercia (?m?????) n (Placename) a kingdom and earldom of central and S England during the Anglo-Saxon period that reached its height under King Offa (757?96)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Mer?ci?a (?m?r ?i ?, -??) n. an early English kingdom in central Britain. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.