| Acronym | Definition |
|---|
| RO | Romania |
| RO | Radio |
| RO | Removal of (medical) |
| RO | Run on (proofreading) |
| RO | Reverse Osmosis |
| RO | Right On |
| RO | Ride-On (Montgomery County, Maryland transit provider) |
| RO | Ragnarok Online (computer game) |
| RO | Royal Oak (Michigan City, MI, USA) |
| RO | Read Only |
| RO | Regional Office |
| RO | Rule Out |
| RO | Rollover (financial) |
| RO | Rovigo (Italy) |
| RO | Readout |
| RO | Reorder (proofreading) |
| RO | Rondônia (Brazilian state) |
| RO | Restraining Order |
| RO | Reliability of Operations |
| RO | Reverse Order |
| RO | Remains Open |
| RO | Radio Operator |
| RO | Red Orchestra (computer game) |
| RO | Registered Owner |
| RO | Reserve Officer |
| RO | Record Only |
| RO | Revenue Officer |
| RO | Responsible Officer |
| RO | Research Only |
| RO | Research Objective |
| RO | Rough Opening (construction) |
| RO | Room Only (hotel) |
| RO | Rock Opera |
| RO | Renewables Obligation (UK) |
| RO | Repair Order |
| RO | Ruimtelijke Ordening (Dutch: spatial development) |
| RO | Risk Officer |
| RO | Russian Orthodox |
| RO | Radiation Oncologist |
| RO | Robust Optimization |
| RO | Required One-Time |
| RO | Ranking Officer |
| RO | Receptor Occupancy (pharmacology) |
| RO | Routine Order (Canadian Military) |
| RO | Reporting Officer |
| RO | RingOut |
| RO | Retired Officer (UK) |
| RO | Remote Operations |
| RO | Rescue Officer |
| RO | Remote Office |
| RO | Tarom Romanian Air Transport (IATA airline code) |
| RO | Recherche Opérationnelle (French: Operations Research) |
| RO | Radar Operator |
| RO | Recognized Organization (various countries) |
| RO | Registration Officer |
| RO | Receive Only |
| RO | Request Order |
| RO | Reactor Operator |
| RO | Requested Off (work schedule) |
| RO | Royal Observatory |
| RO | Regnum Online (video game) |
| RO | Revenue Outturn (UK) |
| RO | Restriction Orifice (device used to drop pressure in a pipe) |
| RO | Resident Office |
| RO | Reviewing Official |
| RO | Requirements Officer |
| RO | Residence Order |
| RO | Raphe Obscurus |
| RO | Range Only (sonobuoy, AN/SSQ-47) |
| RO | Route Order |
| RO | Régime Obligatoire (French: Required Plan; health care) |
| RO | Relay Operator |
| RO | Rate Offset |
| RO | Right Outboard |
| RO | Requirements Objective |
| RO | Requisitioning Objective |
| RO | Radiological Officer |
| RO | Regional Operation (various organizations) |
| RO | Rotate Out (Hyper Logo Turtle Graphics command) |
| RO | Redistribution Order |
| RO | Rutas Orientales (Spanish: Eastern Routes) |
| RO | Routing Office (US Navy) |
| RO | Regrets Only (invitation response) |
| RO | Réponse Objective (French) |
| RO | Registered Optician |
| RO | Reportable Occurrence |
| RO | Resistive Open |
| RO | Routing Organisation |
| RO | Report Orderly |
| RO | US Revenue Private Die Proprietary (Scott Catalogue prefix; philately) |