| Abbreviation | Definition |
|---|---|
| RSO | Rainbow Service Organization |
| RSO | Range Safety Officers |
| RSO | Rapid Sustainment Office |
| RSO | Recognized Security Organization |
| RSO | Recognized Service Organization |
| RSO | Recognized Service Organizations |
| RSO | Recognized Social Organizations |
| RSO | Refinery Safety Overview |
| RSO | Regimental Supply Officer |
| RSO | Regional Sales Office |
| RSO | Regionalny System Ostrzegania |
| RSO | Registered Service Organization |
| RSO | Rent Stabilization Ordinance |
| RSO | Retail Shipment Order |
| RSO | Retirement Services Office |
| RSO | Rick Simpson Oil |
| RSO | Ridiculously Showing Off |
| RSO | Right Salpingo Oophorectomy |
| RSO | Roanoke Symphony |
| RSO | Robert Stigwood |