| Architecture Student Organization | Academic & Science |
| American Society of Ocularists | Academic & Science |
| Algemeen Secundair Onderwijs | Academic & Science |
| A Science Odyssey | Academic & Science |
| Associated Student Organization | Academic & Science |
| Asosa | Airport Code |
| Adelaide Symphony Orchestra | Arts |
| Albany Symphony Orchestra | Arts |
| Amman Symphony Orchestra | Arts |
| AmSouth BanCorporation | Business |
| Administrative Services Only | Business |
| Annapolis Symphony Orchestra | Community |
| Austin Symphony Orchestra | Community |
| American Symphony Orchestra | Community |
| After School Online | Community |
| Arts Support Organization | Community |
| Atlanta Symphony Orchestra | Community |
| Alabama Symphony Orchestra | Community |
| Arkansas symphony orchestra | Community |
| Aids Service Organizations | Community |
| Artistic Skyrim Overhaul | Community |
| Arbitrary Slice Ordering | Computer and Networking |
| Assembler Object | Computing |
| Advanced Security Option | Computing |
| Application Service Object | Computing |
| Advanced System Optimizer | Computing |
| Australian Screen Online | Computing |
| App Store Optimization | Computing |
| Automatic Shutoff | Electronics |
| Assembler Object (object-oriented) File | File Type |
| Astound Dynamite Objects | File Type |
| Analogue Switch Off | General |
| All Safe Outcome | General |
| Automated Systems Operations | General |
| Allele Specific Oligonucleotide | General |
| Authorized Service Outlet | General |
| Amsoil Synthetic Oil | General |
| Automotive Safety Office | General |
| Automotive Strategy Office | General |
| Audi South Orlando | General |
| Auto Services Operator | General |
| Aggregate Storage Option | General |
| Active Simulation Orderedlist | General |
| A Shot Of | General |
| Airborne Snow Observatory | General |
| Administrative Service Organization | General |
| Anat Shenker Osorio | General |
| All Star Outfitters | General |
| A Small Orange | General |
| Associated Students Organization | General |
| App Search Optimisation | General |
| Armored Scrum Object | General |
| App Store Optimisation | General |
| Aircraft Shopper Online | General |
| App Search Optimization | General |
| App Store Optimizing | General |
| App Store Otimization | General |
| Address Supporting Organisation | General |
| Agility Shows Online | General |
| Anvil Shaped Object | Governmental |
| Administrative Services Organization | Governmental |
| Assistant Section Officer | Governmental |
| Administrative Services Only Contract | Healthcare |
| ASANGAON | Indian Railway Station |
| Alianza Sindical Obrera | International |
| Ankara Sanayi Odasi | International |
| Arhivele Statului Oradea | International |
| Arterial Switch Operation | Medical |
| Arteriosclerosis Obliterans | Medical |
| Anti Streptolysin O | Medical |
| AntiStreptolysin O titer | Medical |
| Anti Streptoysin O | Medical |
| Antibiotic Stop Order | Medical |
| Ankle Stabilizer Orthosis | Medical |
| And So On | Messaging |
| Administrative Service Officer | Military and Defence |
| Advanced Special Operations | Military and Defence |
| Air Support Operations | Military and Defence |
| Air Surveillance Officer | Military and Defence |
| Aviation Safety Officer | Military and Defence |
| Address Space Object | Networking |
| Address Supporting Organization | Networking |
| Active Server Optimal | Networking |
| Active Simulation Object | Softwares |
| Amaury Sport Organisation | Sports |
| Amaury Sport Organization | Sports |
| Analog Switch-Off | Technology |