SOS
Concise Oxford English Dictionary © 2008 Oxford University Press:
SOS/esəʊˈes/
▶noun (pl. SOSs) an international coded signal of extreme distress, used especially by ships at sea.
■ an urgent appeal for help.
■ Brit. a message broadcast in an emergency in an attempt to contact an untraceable person.
– origin early 20th cent.: letters chosen as being easily transmitted and recognized in Morse code; by folk etymology an abbrev. of save our souls.
'SOS' also found in these Oxford entries:
