which SO are you referring to? I'm going with Sub-Optimal (with Station Operator coming in a close second) but I just wanted to make sure
SO Significant Other
SO Sistema Operativo (Italian: Operating System)
SO Division Staff Officer
SO Safety Observer
SO Safety Office
SO Safety Officer
SO Sales Order
SO Sales Out
SO Saneringsonderzoek (Dutch: soil remediation research)
SO Sans Opinion (French : No Preference)
SO Schriftelijke Overhoring
SO Science Olympiad
SO Scottish Office
SO Sea Organization (Scientology)
SO Second Officer
SO Sector Outperform (investing)
SO Security Officer
SO Seige Onager (Age of Kings game)
SO Seller's Option
SO Semantic Object
SO Semi-Orthogonal
SO Send Only
SO Senior Officer
SO Sensor Operator
SO Serial Output
SO Server Options
SO Service Object
SO Service Observe
SO Service Order
SO Shaquille O'neal (NBA Player)
SO Shared Object (UNIX)
SO Sheriff's Office
SO Shift-Out
SO Shipment/Shipping Order
SO Show of Oil (drilling reports)
SO Shut Out (sports)
SO Shutout (baseball)
SO Shutout(s) (hockey)
So Siehe Oben (German: see above)
SO Sign Off
SO Sims Online (game)
SO Sistema Operacional (Brazil: Operating System)
SO Slow Oxidative
SO Small-Outline
SO Socket Outlet (British, electrical)
SO Sold Out
SO Solicitation Officer
SO Solid Optical
SO Solothurn (Soleure; Suisse Canton)
SO Somalia
SO Sondrio, Lombardia (Italian province)
SO Source of Orgasm
SO South/Southern
SO Southampton (UK postal code)
SO Southern Airways (airline)
SO Southern Oscillation
SO Spatial Orientation
SO Special Olympics
SO Special Operations
SO Special Order
SO Special Orthogonal (mathematics; group theory)
SO Specialist Operations
SO Stack Overflow
SO Staff Officer
SO Staff Officer (commissioned Police Officer attached to Inspector-General of Police)
SO Standard Oil
SO Standing Order
SO Star Ocean (video game)
SO Station Officer
SO Station Operator
SO Steward Observatory (University of Arizona)
SO Stewardship Ontario (Canada)
SO Stockage Objective(s)
SO Strategic Objective
SO Strategic Outsourcing (IBM)
SO Strike Out
SO Strung Out (band)
SO Stuck Open
SO Student Organization
SO Sub-Optimal
SO Successful Offeror
SO Sud-Ouest (French: south west)
SO Sud-Ovest (Italian: Southwest)
SO Südost/Südosten (German: South-East)
SO Superior Oblique (eye muscle)
SO Supervisor's Office (USDA)
SO Supply Officer
SO Supporting Organization of ICANN
SO Surface Operator (MFD)
SO Switching Office
SO Symphony Orchestra
SO Synchronous Oscillator
SO System Operator
SO System Outage
SO System Overheat
SO System Overload
SO Systems Operations
