(n.) a distress signal
Backronyms are words or phrases that are widely and mistakenly believed purported to be acronyms. Posh, for instance, is often claimed to stand for “port out, starboard home”, a reference to moneyed cruise ship passengers paying for the best views on both the outward and homeward bound parts of their voyage. Golf too is said to stand for “gentlemen only, ladies forbidden” (or ladies do something else that begins with F). And the distress signal SOS is famously claimed to stand for “save our souls”, or “save our ship”.
None of these is true, of course. Posh is simply thought to come from an old slang word for cash or loose change. Golf is probably descended from an old Dutch word for a club, colf or kulf (albeit with perhaps some influence of a Scots word for a stout blow to the head). And the letter combination SOS was chosen as a distress signal for no other reason than that its rhythmic and symmetrical combination of dots and dashes [· · · – – – · · ·] is so immediately noticeable. (Incidentally, precisely the same combination of dots and dashes could also be used to spell the letters “VTB” in Morse code, but the designation SOS was used because of its own symmetry and memorability.)
Before SOS was adopted in the early 1900s, however, the standard telegraph distress signal was “CQD” [– · – · – – · – – · ·]. It’s fair to say that that’s hardly the most recognisable or memorable arrangement of dits and dahs on offer, so why pick that?
Well, on their own the letters “CQ” had long been used as a telegraphic distress signal as they sound identical to the French word sécu, an abbreviation of sécurité. The Marconi Telegraph Company simply added a letter D to this to make their first recommended distress signal, CQD. But just like SOS, CQD also fell foul of backronymy and before long myths had emerged claimed that it stood for “come quickly—danger!”, or “come quickly—drowning!”
Problems with interpreting the confusing set of letters “CQD” over a poor signal, however, eventually led to calls for a more immediately recognizable distress signal to be adopted, and so SOS was officially introduced in 1906.