| Office of Academic Affairs | Academic & Science |
| Online Application for Admission | Academic & Science |
| Office of Academic Advising | Academic & Science |
| Other Academic Appointees | Academic & Science |
| Omega Alpha Academy | Academic & Science |
| Offender Alumni Association | Academic & Science |
| Ogden, Allen, and Associates | Business |
| Oriental Astronomical Association | Business |
| Ontario Association of Architects | Business |
| Opticians Association of America | Business |
| Other Agency Accounts | Business |
| Other Agency | Business |
| Omissions, Alterations and Additions | Business |
| Oxaloacetate | Chemistry |
| Otaku Anime Academy | Community |
| Ohio Achievement Assessment | Community |
| Oakland Activities Association | Community |
| Obstetric Anaesthetists Association | Community |
| Organic Acidemia Association | Community |
| Okinawa Association of America | Community |
| Oakdale Athletic Association | Community |
| On Air Activation | Computer and Networking |
| Open Agent Architecture | Computing |
| One Against All | Computing |
| Open Arcade Architecture | Computing |
| Oracle Advanced Analytics | Computing |
| Ohio Aviation Association | General |
| Oxford Aviation Academy | General |
| Office of the Administrative Assistant | General |
| Overly aggressive anon | General |
| Ohio Assment Achiments | General |
| Other Aquatic Animals | General |
| Over Analyzers Anonymous | General |
| Ohio Achievement Assessments | General |
| oxaloacetate aKG alpha | General |
| Oman Automobile Association | General |
| Online Auto Auction | General |
| Outs Above Average | General |
| Office of Accessibility Accommodation | General |
| Outdoor Adventurous Activities | General |
| Overall Accuracy And | General |
| Outstanding Achievement Award | General |
| Office of Academic Affiliations | Governmental |
| Older Americans Act | Governmental |
| Open Automotive Alliance | Governmental |
| Oklahoma Agents Alliance | Governmental |
| Oregon Accreditation Alliance | Governmental |
| Oklahoma Animal Alliance | Governmental |
| One Agents Alliance | Governmental |
| Optometrists Association Australia | Medical |
| Old Age Assistance | Real Estate |
| Office on African Affairs | Regional |
| Orbiter Access Arm | Space Science |
| Orbiter Alternate Airfield | Space Science |
| Ontario Association of Archers | Sports |