| Office of Student Affairs | Academic & Science |
| Optical Society of America | Academic & Science |
| Open Society Archives | Academic & Science |
| Open Simulation Architecture | Academic & Science |
| Open Systems Architecture | Academic & Science |
| Office of Student Activities | Academic & Science |
| Orissa Society of America | Academic & Science |
| Open Service Architecture | Academic & Science |
| Ontario Society of Artists | Academic & Science |
| Orissa Society of Americas | Academic & Science |
| Optical Spectrum Analyzer | Academic & Science |
| Office of the State Architect | Academic & Science |
| Office of the Science Advisor | Academic & Science |
| Optical Society A | Academic & Science |
| Open Space Agency | Business |
| Orsini Security Agency | Business |
| On Shelf Availability | Business |
| Office of the State Auditor | Business |
| Old Students Association | Community |
| Oakland School for the Arts | Community |
| Order of Saint Augustine | Community |
| Oregon Student Association | Community |
| Old School Arcade | Community |
| Oshkosh Student Association | Community |
| Office Systems Architecture | Computing |
| Out of Service Area | Computing |
| Open Services Architecture | Computing |
| Optical Subassembly | Computing |
| Object Oriented Systems Analysis | Computing |
| Open Source Architecture | Computing |
| Out of Band Services Architecture | Computing |
| Operating System Administrator | Computing |
| Oracle Sales Analyser | Computing |
| Over Sampling | Computing |
| Object Storage Architecture | Computing |
| Open Solutions Alliance | Computing |
| Open Scripting Architecture | Computing |
| Open Standard Architecture | Computing |
| Open Service Access | Computing |
| Online Safety Alliance | Computing |
| Open Society Archive | Computing |
| Open System Authentication | Computing |
| Online Services Advisor | General |
| Open Structure Anti | General |
| Open Systems Adapter | General |
| Only Store Administrative | General |
| Observability Subspace Algorithm | General |
| Outstanding Silliman Awardee | General |
| Orangutans Seem Alert | General |
| Omicsoft Sequence Aligner | General |
| Obstructive sleep apneas | General |
| Out of Station Allowance | General |
| Optical Spectrum Access | General |
| Open Structure Antiglare | General |
| Opportunity Success and Ambition | General |
| Olancho San Agustin | General |
| Over Speed Alarm | General |
| One Step Ahead | General |
| The Office Of Secret Actions | General |
| Output Stuck At | General |
| Online Sexual Addiction | General |
| OutStanding Achievement | General |
| Sleep Apnea | General |
| Organization of Staff Analysts | General |
| Online Signatory Application | General |
| Outstanding Student Award | General |
| Online Scholarship Application | General |
| Obstructive Sleep Apnoea | General |
| on-site assem bly | General |
| Operational Security Assurance | General |
| Office of Shared Accountability | General |
| Optical Shop of Aspen | General |
| Office of Services to the Aging | General |
| Office of Scientific Affairs | General |
| Official Secrets Act | Governmental |
| Open Space Alliance | Governmental |
| Organic Seed Alliance | Governmental |
| AUSA ROAD | Indian Railway Station |
| Office Support Assistant | Jobs |
| Obstructive Sleep Apnea | Medical |
| Overhead Squat Area | Medical |
| Obstructuve Sleep Apnea | Medical |
| Operational Services Agreement | Military and Defence |
| Office of Special Affairs | Military and Defence |
| Office of The Secretary of The Army | Military and Defence |
| Operational Support Airlift | Military and Defence |
| Open System Architecture | Military and Defence |
| Omnibus Service Authority | Networking |
| Osage | Regional |
| Operational Support Area | Space Science |
| Outdoor Soccer of America | Sports |
| Omaha Sports Academy | Sports |
| Ontario Soccer Association | Sports |
| Online Soccer Academy | Sports |
| Oklahoma Soccer Association | Sports |