| Rank | Abbreviation | Meaning |
|---|
| ***** | RIOS | Reactive Infinite-order Sudden (at.-mol. Reactive Collisions)
| |
| ***** | RIOS | Respiratory Illness Opinion Survey
| |
| **** | RIOS | Remote Input Output Stations
| |
| **** | RIOS | River Inputs to Ocean System
| |
| **** | RIOS | Rhode Island Orchid Society
| |
| **** | RIOS | Research Integrity Officers
| |
| **** | RIOS | Research and Innovation for Organizations and Societies
| |
| *** | RIOS | Remote Input Output System
| |
| *** | RIOS | Recycling Industry Operating Standard
| |
| ** | RIOS | Research Internships in Ocean Sciences
| |
| * | RIOS | RIO TINTO CERT (Euronext Brussels [BRU])
| |
| * | RIOS | Radio Infrared Optical Sensors
| |