a radio signal used for calling for help, especially by a ship or plane
View the full definition in the Macmillan Dictionary.
Origin and usage
The noun SOS is the representation of three letters of Morse code, chosen as the international signal of distress because they are easily transmitted and recognized. The signal was used by German shipping from 1905 and was universally adopted following an international conference held in 1908 in order to agree on a single signal.
Many believe that the letters SOS, used to call for help at sea or in the air, stand for ‘Save our Ship’ or even ‘Save our Souls’. In fact the letters don’t stand for anything; they are simply the internationally accepted distress signal, agreed at the beginning of the 20th century as a way for ships at sea to call for help when in difficulties. SOS replaced a number of other signals that were being used by different nations and because the chosen Morse code signal of three dots, three dashes and three dots could be read as the letters S, O, and S this is how the signal came to be known. Today SOS is universally recognized as a call for help; indeed the second meaning in Macmillan Dictionary is ‘an urgent request for help from someone in trouble‘.
“The Coast Guard received the first SOS call at 5.15 pm yesterday.”
“The nonprofit had sent a virtual SOS to supporters last month saying expenses had become unsustainable.”
lifeboat, mayday, rescue
Browse related words in the Macmillan Thesaurus.
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