sort by Rank | Alpha
| Possible Meanings | Rank |
|---|
| Online Research Unit | **** |
| Orange and Rockland Utilities | **** |
| Off Road Unlimited | *** |
| organized research units | *** |
| Oil Recovery Unit | *** |
| Officine Riunite Udine | *** |
| Orbital Replacement Units | *** |
| Ontario Rugby Union | *** |
| Orbit Replaceable Unit | *** |
| operating room use | ** |
| Orbit Replaceable Units | ** |
| Organismo Rappresentativo Universitario | ** |
| Orbital Replaceable Units | ** |
| On Orbit Replaceable Unit | ** |
| Oklahoma Roberts University | ** |
| Optimum Replaceable Unit | ** |
| Optical Repeater Units | ** |
| Observational Results Unsolicited | ** |
| Orbit Replacement Unit | ** |
| Oregon Rowing Unlimited | * |
| Operational Response Unit | * |
| Organizational Research Unit | * |
| Oxygenate Removal Unit | * |
| Orbital Replacable Unit | * |
| Oceanographic Research Utilizing | * |