| FSO | Fabryka Samochodow Osobowych 
| Others |
| FSO | Facilities Service Office
| Others |
| FSO | Facilities Service Order
| Others |
| FSO | Facility Security Officer
| Others |
| FSO | Family and School Organization
| Others |
| FSO | Family Student Organization
| Others |
| FSO | Family Support Organization
| Others |
| FSO | Family Support Organizations
| Others |
| FSO | Fashion Steps Out
| Others |
| FSO | Feature Space Optimization
| Others |
| FSO | Federal Statistical Office
| Others |
| FSO | Feed Schemes Observatory
| Others |
| FSO | Fellowships and Scholarships Office
| Others |
| FSO | Field Selector Outside
| Others |
| FSO | Field Service Organization
| Others |
| FSO | File Secure Object
| Others |
| FSO | File System Object
| Others |
| FSO | Files system object
| Others |
| FSO | Financial Service Organization
| Others |
| FSO | Financial Services Office
| Others |
| FSO | Fire Support Officer
| Others |
| FSO | Fixed Standardized Output
| Others |
| FSO | Flag Service Organization
| Others |
| FSO | Flagstaff Symphony Orchestra
| Others |
| FSO | Flax Seed Oil
| Others |
| FSO | FlightSimulation.org
| Others |
| FSO | Flint Symphony Orchestra
| Others |
| FSO | Floating Storage and Offloading
| Others |
| FSO | Floating Storage Offloading
| Others |
| FSO | Floor Support Officer
| Others |
| FSO | Flotilla Staff Officer
| Others |
| FSO | Footprint Shape Optimization
| Others |
| FSO | For Services Of
| Others |
| FSO | Foreign Service Officer
| Others |
| FSO | Forex School Online
| Others |
| FSO | Forward Support and Observer
| Others |
| FSO | Fountain Square Outfitters
| Others |
| FSO | Four Strokes Only
| Others |
| FSO | Fox Sports Ohio
| Others |
| FSO | Fractional Seat Ownership
| Others |
| FSO | Free Space Optical
| Others |
| FSO | Free Space Optics
| Others |
| FSO | Freestyle Skiing Ontario
| Others |
| FSO | Friday Squadron Operations
| Others |
| FSO | Frito Services Officer
| Others |
| FSO | from surveys of
| Others |
| FSO | Fuel Service Option
| Others |
| FSO | Fuel Service Option (car rental)
| Others |
| FSO | Fuel Shut Off (NOTICE ON METAL PLATES, MACHINERY-EQUIPMENT)
| Others |
| FSO | Fuel Supply Office
| Others |
| FSO | Full Sail Online
| Others |
| FSO | Full Scale Output
| Others |
| FSO | Full Spectrum Oil
| Others |
| FSO | Full Synthetic Oil
| Others |
| FSO | Full-Scale Output
| Others |
| FSO | Fulltext Sources Online
| Others |
| FSO | Functional Supplementary Objective
| Others |
| FSO | Functional Support Office
| Others |
| FSO | Fund for Special Operations
| Others |
| FSO | Future State Outsourcing
| Others |
| FSO | The File Systems Object
| Others |
| FSO | The Flight Safety Organization
| Others |