ill-na·tured (?l?n??ch?rd)adj.1. Having a disagreeable, irritable, or malevolent disposition.2. Spiteful; nasty: an ill-natured retort.ill?-na?tured·ly adv.ill?-na?tured·ness n.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.ill-natured adj naturally unpleasant and mean ?ill-?naturedly adv ?ill-?naturedness nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ill?-na?tured adj. having or showing an unpleasant disposition. [1625?35] ill?-na?tured?ly, adv. ill?-na?tured?ness, n. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.