sort by Rank | Alpha
| Possible Meanings | Rank |
|---|
| Park Recreation and Open Space | **** |
| Pediatric Research in Office Settings | **** |
| Pug Rescue of Sacramento | *** |
| Philips Radiation Oncology Systems | *** |
| Police Reporting and Occurrence System | *** |
| Public Record Office Standard | *** |
| Population Research and Outcome Studies | *** |
| partially reduced O2 species | ** |
| partially reduced oxygen species | ** |
| pathogen-related oral spirochete | ** |
| pathogen-related oral spirochetes | ** |
| Psychosocial Review of Systems | ** |
| Pounds Remote Ordering System | ** |
| Paediatric Radiation Oncology Society | ** |
| care-Pediatric Research in Office Settings | ** |
| Promoting Researchers Online Supervision | ** |
| Personal Recovery Oriented Services | ** |
| Planning Resources and Operations Systems | ** |
| Pricing Revenue Optimization Software | ** |
| Personalized Recovery Oriented Services | ** |
| Partners and Resources for Operational Safety | ** |
| Parks River and Open Space | ** |
| Peninsula Radio Operators Society | ** |
| Police Reporting Occurrence System | ** |
| Peer Review Online System | * |
| Practical Response to Oil Spills | * |
| Professional Review and Operational Shoppers | * |
| Professional Reactor Operator Society | * |