Ad·e·laide (?d?l-?d?) A city of southern Australia northwest of Melbourne. Founded in 1836, Adelaide is the capital of South Australia.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.Adelaide (?æd??le?d) n (Placename) the capital of South Australia: Port Adelaide, 11 km (7 miles) away on St Vincent Gulf, handles the bulk of exports. Pop: 1 225 235 (2011)Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Ad?e?laide (?æd l?e?d) n. a city in and the capital of South Australia, in Australia. 1,050,000. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.