| ONS | Object Name Service 
| Others |
| ONS | Object Naming Service
| Others |
| ONS | Odyssey Nail Systems
| Others |
| ONS | Office for National Statistics
| Others |
| ONS | Office of National Statistics
| Others |
| ONS | Office of Naval Science
| Others |
| ONS | Office of Neighborhood Safety
| Others |
| ONS | Office of Noddy Statistics
| Others |
| ONS | Office of Nursing Services
| Others |
| ONS | Office of Nutrition Services
| Others |
| ONS | Official Nintendo Seal
| Others |
| ONS | Offshore North Sea
| Others |
| ONS | Offshore Northern Seas
| Others |
| ONS | Om Namah Shivaya
| Others |
| ONS | Oncology Nursing Service
| Others |
| ONS | Oncology Nursing Society
| Others |
| ONS | One Name Study
| Others |
| ONS | One Night Stands
| Others |
| ONS | Onslow, Western Australia, Australia
| Others |
| ONS | Open Network Services
| Others |
| ONS | Open Network Summit
| Others |
| ONS | Open Networking Summit
| Others |
| ONS | Operational Needs Statement
| Others |
| ONS | Optical Nerve Sheath
| Others |
| ONs | Optical Nerves
| Others |
| ONS | Optical Network Service
| Others |
| ONS | Optical Networking Services
| Others |
| ONS | Optical Networking System
| Others |
| ONS | Optical Networks Systems
| Others |
| ONS | Oranje Nassau Sneek
| Others |
| ONS | Oriental Numismatic Society
| Others |
| ONS | Original Night Stalker
| Others |
| ONS | Orthopaedic Neurosurgery Specialists
| Others |
| ONS | Other Nervous System
| Others |
| ONS | Ottawa Neighbourhood Study
| Others |
| ONS | Outstanding New Student
| Others |