no-fly zone (n??fl??)n. Airspace in which certain aircraft, especially military aircraft, are forbidden to fly.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.no-fly zone n 1. (Military) an area in which aeroplanes may not fly, esp during wartime 2. a taboo subject Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014no?-fly? zone` n. an area over which no military flights are allowed. [1991] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.