I·seult (?-so?olt?) also I·sol·de (?-s?l?d?, ?-z?l?-)n. In Arthurian legend, an Irish princess who married the king of Cornwall and had a love affair with his knight Tristan.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.Iseult (??su?lt) or Yseult; Isolde (??z??ld?) (in Arthurian legend) n1. (European Myth & Legend) an Irish princess wed to Mark, king of Cornwall, but in love with his knight Tristan2. (European Myth & Legend) (in another account) the daughter of the king of Brittany, married to TristanCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014I?seult or Y?seult (??sult) n. a heroine of Arthurian legend, the wife of King Mark of Cornwall and the lover of Tristram. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.