Ba·ja California (bä?hä) also Lower California A mountainous peninsula of western Mexico extending south-southeast between the Pacific Ocean and the Gulf of California south of the US border.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.Baja California (?baeh?) n1. (Placename) the Spanish name for Lower California2. (Placename) short for Baja California NorteCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Ba?ja Califor?nia (?b? h?) n. a peninsula in NW Mexico between the Gulf of California and the Pacific. Also called Ba?ja, Lower California. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.