asdic (?æzd?k) n (Electronics) an early form of sonar[C20: from A(nti-)S(ubmarine) D(etection) I(nvestigation) C(ommittee)]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014so?nar (?so? n?r) n. 1. a method for detecting and locating objects submerged in water by echolocation. 2. the apparatus used in sonar. [1940?45; so(und)na(vigation)r(anging)] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.