tone-deaf (t?n?d?f?)adj.1. Unable to distinguish differences in musical pitch.2. Unable to appreciate or understand the concerns or difficulties of others; out-of-touch.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.tone-deaf adj (Pathology) unable to distinguish subtle differences in musical pitch tone deafness nCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014tone?-deaf` adj. unable to distinguish differences in musical sounds when producing or hearing them. [1890?95] tone? deaf`ness, n. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.