| Oxygen-Evolving System | Academic & Science |
| Oakland Early College | Academic & Science |
| Osbourne Engineering Company | Academic & Science |
| Osborne Engineering Company | Academic & Science |
| Oklahoma Electric Cooperative | Academic & Science |
| Ontario Engineering Competition | Academic & Science |
| Olfactory Ensheathing Cells | Academic & Science |
| Ordre Des Experts Comptables (france) | Accounts and Finance |
| Ocussi | Airport Code |
| Otis Elevator Company | Business |
| Oil Exploration Company | Business |
| Orbital Corporation Ltd | Business |
| Optic Edge Corporation | Business |
| Office Environment Company | Business |
| Office Equipment Company of Mobile | Business |
| Open Education Consortium | Community |
| Ouachita Enterprise Community | Community |
| Outdoor Education Center | Community |
| Old Earth Creationism | Community |
| Open Enterprise Computing | Computing |
| Output Edge Control | Computing |
| Oracle Engagement Cloud | Computing |
| Oman e-Commerce Conference | Computing |
| Opus Embedded Command | Computing |
| Offshore Engineered Component | Computing |
| Orion Engineered Carbons | General |
| Online Ethics Center | General |
| Elite CFD | General |
| Overly Excessive Crap | General |
| Original Equipment Cost | General |
| Old Ellicott City | General |
| Oxygen Evolution Catalyst | General |
| Orbital Engine Corporation | General |
| Ordinem Ecentrici Coctores | General |
| Office of Emergency Communications | General |
| Office of Early Childhood | General |
| Oxygen Evolving Complex | General |
| Opportunties in Emergency Care | General |
| Ohio Empowerment Coalition | General |
| Oregon Evidence Code | General |
| Open Ended Contract | General |
| Ordinem Eccentrici Coctores | General |
| Only Envying Clowns | General |
| Old Earth Creation | General |
| Odd Engineering Contraption | General |
| The Order Of Eternal Champions | General |
| Organization Executive Course | General |
| Overall Evaluation Criterion | Governmental |
| Overseas Employment Corporation | Governmental |
| Oregon Environmental Council | Governmental |
| Office of Environmental Coordination | Governmental |
| Ocean Energy Council | Governmental |
| Oregon Employer Council | Governmental |
| Ohio Environmental Council | Governmental |
| Observatory of Economic Complexity | Governmental |
| Overseas Employment Certificate | Governmental |
| Offshore Engineered Components | Governmental |
| Online Education Courses | Internet |
| Oxygen Equilibrium Curve | Medical |
| Olfactory Ensheating Cell | Medical |
| Outdoor Emergency Care | Medical |
| Operational Evaluation Command | Military and Defence |
| Ocussi, Indonesia | Regional |
| Orange Empire Conference | Sports |
