swimming pooln. A structure, often a concrete-lined excavation of rectangular shape, that is filled with water and used for swimming.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.swimming pool n (Swimming, Water Sports & Surfing) an artificial pool for swimming Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014swim?ming pool` n. a tank or large artificial basin, as of concrete, for filling with water for swimming. [1895?1900] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.