| Acronym | Definition |
|---|
| SSO | Single Sign-On |
| SSO | Sanitary Sewer Overflow |
| SSO | Ship Security Officer |
| SSO | Singapore Symphony Orchestra |
| SSO | Social Security Office |
| SSO | Syracuse Symphony Orchestra (Syracuse, New York) |
| SSO | Society of Surgical Oncology |
| SSO | Shared Storage Option (VERITAS Software Corporation) |
| SSO | Shared Services and Outsourcing |
| SSO | Sydney Symphony Orchestra |
| SSO | Sun Synchronous Orbit |
| SSO | Standard-Setting Organization |
| SSO | Sequence-Specific Oligonucleotide (Probes; genotyping) |
| SSO | Simultaneous Switching Output |
| SSO | Senior Scientific Officer (UK) |
| Sso | Sulfolobus Solfataricus |
| SSO | Site Safety Officer |
| SSO | School Support Organization |
| SSO | Source Selection Official |
| SSO | Senior Staff Officer |
| SSO | Social Security Organization (Laos) |
| SSO | Site Security Officer |
| SSO | Shared Service Organization |
| SSO | Shattered Sun Offensive (gaming, World of Warcraft) |
| SSO | Stateful Switch Over (Cisco) |
| SSO | Social Security Offset |
| SSO | Space Shuttle Orbiter |
| SSO | Sahara and Sahel Observatory |
| SSO | Sandia Site Office |
| SSO | Senior Station Officer (fire service; Australia and New Zealand) |
| SSO | Staff Security Officer (NSA) |
| SSO | Specific Spoilage Organism (food protection) |
| SSO | Safety/Security Officer |
| SSO | Scleroderma Society of Ontario |
| SSO | Spatial Standard Observer (aeronautics) |
| SSO | Satellite Switching Office |
| SSO | Südsüdost (German; South-South-East) |
| SSO | Sud-Sud-Ovest (Italian: South-South-West) |
| SSO | Ship Safety Officer |
| SSO | Support Services Organization |
| SSO | Space Systems Operations |
| SSO | System Support Office |
| SSO | Scottsdale Symphony Orchestra (Arizona) |
| SSO | Survey Software Online (Addison, TX) |
| SSO | Sammamish Symphony Orchestra (Issaquah, WA) |
| SSO | Survivors Speak Out (UK support group for those who have attempted suicide) |
| SSO | Studio Symphony Orchestra (Northern Ireland) |
| SSO | Switch Socket Outlet |
| SSO | Sheriff's Special Officer (Orange County, California) |
| SSO | Single Second Order |
| SSO | Special Security Office/r |
| SSO | Sherman Symphony Orchestra (Sherman, TX) |
| SSO | Starlight Symphony Orchestra (Texas) |
| SSO | Secondary Significant Other (polyamory) |
| SSO | Sudano-Sahelian Office (UN) |
| SSO | Sorry Sold Out |
| SSO | Same-Sex Oriented |
| SSO | Support System for OEX (Orbital Experiments; NASA) |
| SSO | Speech Service Option |
| SSO | Synchronization Staff Officer |
| SSO | Suncoast Symphony Orchestra (Tampa Bay, FL) |
| SSO | Seaward Security Officer |
| SSO | Soft Skill Optimierung |
| SSO | System Synchronization Officer |
| SSO | Service Support Office |
| SSO | Store Specific Order (retailing) |
| SSO | Switching & Signaling Operations (Sprint) |
| SSO | Switch Specific Overhead |
| SSO | Shadow Stalkers Organization |
| SSO | Safety Services Officer |
| SSO | System Support Organization |
| SSO | Slight Show of Oil (drilling reports) |
| SSO | System Security Office/Officer |
| SSO | System Staff Officer |
| SSO | Supply Support Operations |
| SSO | Special Systems Operation |
| SSO | Saginaw Symphony Orchestra (Saginaw, Michigan) |
| SSO | Signal Security Office/Officer |
| SSO | Scarborough Symphony Orchestra (UK) |
| SSO | Surveillance Systems Operator |
| SSO | Steady-State Optimization |
| SSO | System Supervisor Overview (training course segment) |
| SSO | Swiftwater Safety Operations |
| SSO | Special Support Office |
| SSO | Server-Side Object (computing) |
| SSO | Seguro Social Obligatorio (Spanish: Compulsory Social Security; various locations) |
| SSO | Standard Service Offer (energy) |
| SSO | Students Speak Out (est. 2007) |
| SSO | Swap Statement Operator |
| SSO | Social Search Optimization |