| Acronym | Meaning |
| ROM | Read Only Memory |
| ROM | Regional Oxidant Model |
| ROM | Reverse Osmosis Membrane |
| ROMNET | Regional Ozone Modeling For Northeast Transport |
| ROMP | Restricted Open-shell Moeller-Plesse |
| ROMP | Ring-opening Metathesis Polymerization |
| RON | Research Octane Number |
| RONALD | Rocketborne Optical Neutral Gas Analyzer With Laser Diodes |
| ROP | Ring-opening Polymerization |
| ROS | Reactive Oxygen Species |
| ROS | Restricted (or Roothaan) Open-shell (Hamiltonian) |
| ROSAT | Roentgen Satellite |
| ROSDAL | Representation Of Organic Structure Description Arranged Linearly |
| ROSE | Regional Oxidants In The SouthEast |
| ROSE | Research On Ozone In The Stratosphere And Its Evolution |
| ROSE | Residual Organic Substance Emissions |
| ROSE | Remote Optical Sensing Of Emissions |
| ROSE | Residual Oil Supercritical Extraction |
| ROSH | Registry Of Occupational Safety And Health |
| ROSINA | Rosetta Orbiter Spectrometer For Ion And Neutral Analysis |
| ROSS | River Oil Spill Simulation |
| ROSS2 | River Oil Spill Simulation 2 Layer Model |
| ROV | Remotely Operated Vehicle |
| ROVP | Reactance Operator Variational Principle |
| ROWPU | Reverse Osmosis Water Purification Unit |
| RP | Reinforced Plastics |
| RP/C | Reinforced Plastics/composite |
| RP/M | Reinforced Plastics/mortar |
| RPA | RNase Protection Assay |
| RPA | Random Phase Approximation |
| RPAE | Random Phase Approximation With Exchange |
| RPC | Regional Planning Commission |
| RPC | Rotation Planar Chromatography |
| RPC | Reduced Potential Curve (method For Anal. Of Potential Functions And Spectra Of Diatomic Molecules) |
| RPC | Reversed-phase Chromatography |
| RPCR | Restricted Principal Component Regression |
| RPCVD | Remote Plasma-enhanced Chemical Vapor Deposition |
| RPD | Relative Percent Difference |
| RPD | Retarding Potential Difference |
| RPDWR | Revised Primary Drinking Water Regulations |
| RPE | Retinal Pigment Epithelium |
| RPECVD | Remote Plasma-enhanced Chemical-vapor Deposition |
| RPEHMO | Relativistically Parametrized Extended Hueckel MO |
| RPF | Renal Plasma Flow |
| RPI | Radius Polydispersity Index |
| RPIPC | Reversed-phase Ion-pair Chromatography |
| RPJ | Radio-frequency Plasma Jet |
| RPL | Radio Photoluminescence |
| RPLC | Reversed-phase Liquid Chromatography |
| RPM | Regional Project Managers |