| Acronym | Definition |
|---|
| ROS | Reactive Oxygen Species |
| ROS | Review of Systems |
| ROS | Return On Sales |
| ROS | Run of Site |
| ROS | Rites of Spring |
| ROS | Registers of Scotland |
| ROS | Raggruppamento Operativo Speciale (Italian Carabinieri Special Forces) |
| ROS | Robot Operating System |
| ROS | Rod Outer Segment (Ophthalmology) |
| ROS | Random Orbital Sander |
| ROS | Rate of Spread (wildland fire behavior expressed in chains per hour; 1 chain = 66 feet) |
| ROS | Record of Service (USMC) |
| ROS | Republic of Singapore (founded 1965) |
| ROS | Read-Only Storage |
| ROS | Royal Order of Scotland (Scottish Rite Honorary Order) |
| ROS | Report Of Survey |
| ROS | Run-On Sentence |
| ROS | Review Of System |
| ROS | Residual Oil Saturation |
| ROS | Run Of Schedule |
| ROS | Review of Symptoms (medical) |
| ROS | Run Of Station |
| ROS | Remote Operations Services |
| ROS | Rain-on-Snow (meteorological event) |
| RoS | Races of Stone (roleplaying games, Dungeons & Dragons) |
| ROS | Report of Sale |
| ROS | Reed Organ Society |
| ROS | Resident Operating System |
| ROS | Rapport d'Ondes Stationnaires (French) |
| ROS | Raster Output Scanner |
| ROS | Required On-Site (Date) |
| ROS | Return From Overseas |
| ROS | Refractory Organic Substances |
| ROS | Religious Orders Study |
| ROS | Region of Support |
| ROS | Rosario, Santa Fe, Argentina - Fisherton (Airport Code) |
| ROS | Relief On Station (UAVs) |
| ROS | Russian Orbital Segment |
| ROS | Research Operations Support |
| ROS | Remote Operator Station |
| ROS | Restoration of Service |
| ROS | Ramapo Orchid Society (New Jersey) |
| ROS | Reviewing Official Statement (performance evaluation) |
| ROS | Recreation Opportunity System (USFS/BLM) |
| ROS | Registrar of Shipping |
| ROS | Resource Object Store |
| ROS | Release of Shift |
| ROS | Required on Station |
| ROS | Reactor Overflow System |
| ROS | Range Operations Support |
| ROS | Restaurant Operations Support |
| ROS | Régiment des Opérations Spéciales (French: Special Operations Regiment) |
| ROS | Register of Society |
| ROS | Rear Observation System |
| ROS | Rapid Obscuration System |
| ROS | Remotely Operated Shutter |
| ROS | Reconstitution Operational State |
| ROS | Reduced Operation/al Status |
| ROS | Report Organization Subsystem |
| ROS | Representative Observing Site |
| ROS | Re-Order Structure |
| ROS | Ramsgate Operatic Society |
| ROS | Resistant Ovary Syndrome |
| ROS | Riddle of Steel (band) |
| ROS | Right of Survivorship |
| ROS | Regional Open Space (various locations) |