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the letters represented by the radio telegraphic signal (· · · – – – · · ·) used, especially by ships in distress, as an internationally recognized call for help.
any call for help: We sent out an SOS for more typists.
verb (used without object)
to send an SOS.
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Origin of SOS

1905–10, from the Morse code alphabet, in which three dots (or short clicks) represents the letter S and three dashes (or long clicks) represents the letter O

Other definitions for SOS (2 of 3)


abbreviation Slang.
shit on a shingle (a euphemistic initialism used to avoid explicit vulgarity).

Other definitions for SOS (3 of 3)


(in prescriptions) if necessary.

Origin of s.o.s.

From Latin sī opus sit
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does SOS mean?

The letter sequence SOS (pronounced S-O-S) is used in Morse code as a distress signal—a way to call for help during an emergency, such as on a ship.

Morse code uses clicks and pauses, short and long sounds, or flashes of light to represent letters and numbers. S is represented by three short clicks or brief flashes of light, and O is represented by three long sounds or longer flashes of light (depicted with dashes).

Morse code can be written out using dots to represent short clicks and dashes to represent long ones, resulting in a specific sequence for SOS (··· – – – ···) that was chosen since it would be easy to communicate with sounds over radio or with flashes of light.

The signal became well-known enough that SOS came to be used as an informal term for any call for help or notification that there is an emergency, as in Send an SOS to the board letting them know that we’ll have to schedule an emergency meeting. 

When used this way, each letter is still pronounced individually (S-O-S). The plural of SOS can be written as SOSs or SOS’s. SOS can also be used as a verb meaning to send such an SOS.

Example: I have my phone set up to automatically send an SOS to certain contacts if I ever dial 9-1-1.

Where does SOS come from?

SOS was officially designated as a distress call in the early 1900s. Contrary to popular belief, the sequence SOS was not meant to stand for “save our ship” or “save our souls,” both of which were applied to the series of letters later. In fact, the letters were not intended to stand for anything—they were chosen simply because they are easy to communicate in Morse code and the resulting sequence is easy to distinguish from any other message.

Morse code has since largely fallen out of practical use in favor of systems based on more advanced technologies, especially satellite communication. However, use of the term SOS as an informal way of referring to a distress call is still common.

Did you know ... ?

What are some other forms of SOS?

  • SOSs (plural)
  • SOS’s (plural)

What are some synonyms for SOS?

What are some words that often get used in discussing SOS?


How is SOS used in real life?

The signal SOS was once commonly used in the context of radio communication among ships. Today, the use of SOS as a general way to refer to a call for help is informal. It’s sometimes used in situations that aren’t quite emergencies—you might text an SOS to your roommate to bring home ice cream, for example.


Try using SOS!

Is SOS used correctly in the following sentence? 

My neighbor’s dog is lost, so I just posted an SOS on the neighborhood message board.

How to use SOS in a sentence

British Dictionary definitions for SOS


an internationally recognized distress signal in which the letters SOS are repeatedly spelt out, as by radio-telegraphy: used esp by ships and aircraft
a message broadcast in an emergency for people otherwise unobtainable
informal a call for help

Word Origin for SOS

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 & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012