| Acronym | Definition |
|---|
| PSO | Particle Swarm Optimization |
| PSO | Phantasy Star Online |
| PSO | Pakistan State Oil |
| PSO | psoriasis |
| PSO | Polycystic Ovary Syndrome |
| PSO | Penalty Shoot-Out (football / soccer) |
| PSO | Pressure Shut Off |
| PSO | Patient Safety Organization (Rockville, MD) |
| PSO | Phone Sex Operator |
| PSO | Power System Operator (various locations) |
| PSO | Peace and Stability Operations (US Army) |
| PSO | Princeton Symphony Orchestra (Princeton, NJ) |
| PSO | Portland Symphony Orchestra (since 1923; Portland, Maine) |
| PSO | Pedicle Subtraction Osteotomy (neurosurgery) |
| PSO | Plastic Small Outline Package |
| PSO | Provisioning Service Object |
| PSO | Photo Studio Optimizer |
| PSO | Progressive Scan Output |
| PSO | Peace Support Operation |
| PSO | Public Service Obligation (chiefly European) |
| PSO | Parent Support Organization |
| PSO | Port Security Officer |
| PSO | Prozess Standard Offsetdruck (German: Process Standard Offset) |
| PSO | Pre-Service Orientation (various organizations) |
| PSO | Principal Scientific Officer |
| PSO | Professional Services Organization |
| PSO | Protected Species Observer |
| PSO | Public Safety Officer |
| PSO | Project Support Office (project management) |
| PSO | Provider Sponsored Organization |
| PSO | Professional Staff Organization (various organizations) |
| PSO | Provincial Sport Organization (Canada) |
| PSO | Post Security Officer (US DoD) |
| PSO | Prohibited Steps Order (UK court order) |
| PSO | Protocol Supporting Organization (ETSI, IETF, ITU, W3C Consortium) |
| PSO | Proprietary Security Officer (various companies) |
| PSO | Philips Symfonie Orkest (Dutch: Philips Symphony Orchestra) |
| PSO | Poker Source Online (gambling) |
| PSO | Product Support Office |
| PSO | Policy Support Officer (various locations) |
| PSO | Political Science Organization (various locations) |
| PSO | Public Service of Oklahoma |
| PSO | Private Sector Operator |
| PSO | Personal Service Organization |
| PSO | Post Secondary Option (education) |
| PSO | Product and Service Offer |
| PSO | Program Secretarial Officer |
| PSO | Password Settings Object |
| PSO | Processing Services Operation (Sprint) |
| PSO | Peoria Symphony Orchestra (Illinois) |
| PSO | Partner Solution Offering (Dell) |
| PSO | Partnership for Sustainable Oceans |
| PSO | Provisioning Service Object (computing) |
| PSO | Pantex Site Office (Amarillo, TX) |
| PSO | Prep Sports Online (high school sports websites) |
| PSO | Process Sign-Off |
| PSO | PlayStationOne |
| PSO | Parcel Shipping Order (various companies) |
| PSO | Paralegal Society of Ontario |
| PSO | Pasto, Colombia - Cano (Airport Code) |
| PSO | Participating Standards Organization |
| PSO | Publicity Security Officer (US Navy) |
| PSO | Piano-Shaped Object (shoddily made or badly damaged piano) |
| PSO | Portsmouth Symphony Orchestra (Portsmouth, OH) |
| PSO | Procurement Support Office |
| PSO | Pembroke Symphony Orchestra (Canada) |
| PSO | Peter Skene Ogden Secondary (school) |
| PSO | Plan de Sécurité Opérateur (French: Safety Plan Operator) |
| PSO | Production Sign Off |
| PSO | Project Safety Officer |
| PSO | Primary Strike Objective |
| PSO | Permanent Slow Order (railway) |
| PSO | Protectseniors.org (Washington, DC lobby) |
| PSO | Primary Standardization Office |
| PSO | Practice/Study/Observation (various universities) |
| PSO | Program Staff Office/Officer |
| PSO | Provisions Supply Office |
| PSO | Preliminary Screening Officer |
| PSO | Proud Social Outcast |
| PSO | Payload Sensor Operator |
| PSO | Possible Survivable Options |
| PSO | Project Step Off |
| PSO | Primary Support Official |
| PSO | Policy Service Office (insurance) |
| PSO | Plan for Safe Operation |
| PSO | Polysporin Ointment |
| PSO | Parma Symphony Orchestra (Parma, OH) |