SOS (?s??-?s?)n.1. The letters that are represented by the Morse code signal · · · – – – · · ·, used as an international distress signal, especially by ships and aircraft.2. A call or signal for help.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.SOS n 1. (Telecommunications) an internationally recognized distress signal in which the letters SOS are repeatedly spelt out, as by radiotelegraphy: used esp by ships and aircraft 2. (Broadcasting) a message broadcast in an emergency for people otherwise unobtainable 3. informal a call for help [C20: letters chosen as the simplest to transmit and receive in Morse code; by folk etymology taken to be an abbreviation for save our souls]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014SOS (??s?o???s) n., pl. SOSs, SOS’s. 1. an internationally recognized radiotelegraphic distress signal, used esp. by ships and consisting of the letters SOS spelled out in Morse Code (?????????). 2. any call for help. [1905?10] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.