From Longman Dictionary of Contemporary EnglishSOSSOS /ˌes əʊ ˈes $ -oʊ-/ noun [singular] 1 TTTCTa signal or message that a ship or plane sends when it is in danger and needs help → mayday2 TCBMESSAGEan urgent message that someone is in trouble and needs help This is an SOS for a Mr Tucker, whose mother is seriously ill.
Examples from the Corpus
SOS• He then requested flares for landing and then put out an SOS that they were on fire.• An SOS talisman is obtainable at many chemists.• Their frantic SOS message was picked up by a Coast Guard vessel.• I mean, are we the only ones who heard the SOS?• Roebuck was visiting his family at Bathurst, about five hours drive west of Sydney, when he received the SOS call.• The civilian operator who took the SOS call may have heard the voice of her killer.• This is a textbook position in which to use the SOS redouble.Origin SOS (1900-2000) S and O, letters chosen because they were easy to send by Morse code, but often understood as short for "save our souls" 