What does SO stand for?

[aitian 0]

My own opinion is that everybody should just type out fully what they want to say. Typing on a full keyboard is so easy and quick that the only place I can understand a need for abbreviations is on a telephone keyboard. Also will lead to less confusion since there seems to be more than one meaning for the same abbreviation like ETA which is pretty much accepted as 'Estimated Time of Arrival' everywhere.

[Ladylethal 12]

I use SO when I dunno if the person is fiance, fiancee, husband or wife, sometimes you dunno if the person talking is male or female so I just say Significant Other, SO.