in·a·bil·i·ty (?n??-b?l??-t?)n. Lack of ability or means.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.inability (??n??b?l?t?) nlack of ability or means; incapacityCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014in?a?bil?i?ty (??n ??b?l ? ti) n. lack of ability. [1400?50; late Middle English