SO /S-O/ n.
1. (also `S.O.') Abbrev. for Significant Other, almost invariably written abbreviated and pronounced /S-O/ by hackers. Used to refer to one's primary relationship, esp. a live-in to whom one is not married. See MOTAS, MOTOS, MOTSS. 2. [techspeak] The Shift Out control character in ASCII (Control-N, 0001110).