SOS does not stand for anything!
SOS is a very easily recognized set of morse code characters
Prior to the introduction of SOS, the morse code distress call was CQD
CQ is a general call (as in seek you)
The D was added to indicate distress
But CQD is _ ._ . _ _._ _.. (dah-di-dah-dit, dah-dah-di-dah, dah-di-dit), which is not easily recognizable in the din of noise that exists on short wave radio bands.
Another problem is that, following a normal CQ, the person transmitting sends the characters DE (meaning from) and his call sign. If the CQ and the DE are too close together, the call could be confused as CQD (E is just a single dot and could easily be lost in the noise).
SOS is much, much easier to recognize
Ham radio operator