ag·no·sia (?g-n??zh?)n. Loss of the ability to interpret sensory stimuli, such as sounds or images.[Greek agn?si?, ignorance : a-, without; see a-1 + gn?sis, knowledge (from gign?skein, to know; see gn?- in Indo-European roots).]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.agnosia (æ??n??z??) n (Psychology) psychol loss or diminution of the power to recognize familiar objects or people, usually as a result of brain damage[C20: New Latin, from Greek agn?sia, from a- without + gn?sis knowledge] ag?nosic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ag?no?sia (æg?no? ??, -?i ?, -zi ?) n. Psychiatry. partial or total inability to recognize objects by use of the senses. [1895?1900;