ill humorn. An irritable state of mind; surliness.ill?-hu?mored (-m?rd) adj.ill?-hu?mored·ly adv.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?-hu?mor n. a disagreeable or surly mood. [1560?70] ill?-hu?mored, adj. ill?-hu?mored?ly, adv. ill?-hu?mored?ness, n. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.