| R&D | Research And Development | - | Computer Acronyms(common) |
| R-CNDO/1X | Relativistic Complete Neglect Of Differential Overlap (method) | - | Computer Acronyms(common) |
| R-GVB | Resonating-generalized Valence Bond (wave Function) | - | Computer Acronyms(common) |
| R2PI | Resonant Two-photon Ionization | - | Computer Acronyms(common) |
| RA | Reduced Aggregate (interplanetary Dust Particle) | - | Computer Acronyms(common) |
| RA | Remedial Action | - | Computer Acronyms(common) |
| RAA | Rigid-atom Approxn. (in Electronic Structure Calcns.) | - | Computer Acronyms(common) |
| RAAS | Renin-angiotensin-aldosterone System | - | Computer Acronyms(common) |
| RABITS | Rolling-assisted Biaxially Textured Substrates | - | Computer Acronyms(common) |
| RAC | Reference Air Concentration (USEPA) | - | Computer Acronyms(common) |
| RACE | Rapid Amplification Of CDNA Ends | - | Computer Acronyms(common) |
| RACE | Reactive Accelerated Cluster Erosion | - | Computer Acronyms(common) |
| RACER | Research On Antarctic Coastal Ecosystem Rates | - | Computer Acronyms(common) |
| RACI | Royal Australian Chem. Institute | - | Computer Acronyms(common) |
| RACM | Reasonably Available Control Measures | - | Computer Acronyms(common) |
| RACM | Regional Atm. Chem. Mechanism | - | Computer Acronyms(common) |
| RACS | Response Action Contractors | - | Computer Acronyms(common) |
| RACS | Raw Agricultural Commodities | - | Computer Acronyms(common) |
| RACT | Reasonably Available Control Technology | - | Computer Acronyms(common) |
| RADM | Regional Acid Deposition Model | - | Computer Acronyms(common) |
| RADREM | Radioactivity Research And Environmental Monitoring Committee | - | Computer Acronyms(common) |
| RADW | Rotationally-adiabatic Distorted-wave | - | Computer Acronyms(common) |
| RAF | Reactivity Adjustment Factor | - | Computer Acronyms(common) |
| RAFA | Rank Annihilation Factor Analysis | - | Computer Acronyms(common) |
| RAFT | Reversible Addition-fragmentation Chain Transfer [polymerization] | - | Computer Acronyms(common) |
| RAG | Risk Assessment Guideline | - | Computer Acronyms(common) |
| RAGE | Receptor For Advanced Glycation Endproducts | - | Computer Acronyms(common) |
| RAGS | Risk Assessment Guidelines For Superfund Sites | - | Computer Acronyms(common) |
| RAHB | Resonance-assisted Hydrogen Bond | - | Computer Acronyms(common) |
| RAILE | Retro-Assisted Imaging Laser Experiment | - | Computer Acronyms(common) |
| RAIN | Reactions And Intermediates Network | - | Computer Acronyms(common) |
| RAINBOWS | Reduced And INternally Biased Oxide Wafers | - | Computer Acronyms(common) |
| RAINS | Regional Acidification Information And Simulation | - | Computer Acronyms(common) |
| RAIRS | Reflection/absorption Infrared Spectroscopy | - | Computer Acronyms(common) |
| RAL | Recommended Allowable Limit | - | Computer Acronyms(common) |
| RALLS | Right-angle Laser Light Scattering | - | Computer Acronyms(common) |
| RAM | Random Access Memory | - | Computer Acronyms(common) |
| RAM | Reference-system Average Mayer-function (in Perturbation Theory) | - | Computer Acronyms(common) |
| RAM | Renormalized Atom Model (for Electronic-structure Calcns.) | - | Computer Acronyms(common) |
| RAM | Restricted Area Molding | - | Computer Acronyms(common) |
| RAMAN | Regional Atmospheric Measurement And Analytical Network | - | Computer Acronyms(common) |
| RAMC | Risk Assessment And Management Commission | - | Computer Acronyms(common) |
| RAMP | Receptor Activity Modifying Protein | - | Computer Acronyms(common) |
| RAMS | Regional Air Monitoring System | - | Computer Acronyms(common) |
| RAN | Residual Acrylonitrile | - | Computer Acronyms(common) |
| RANTES | Regulated On Activation Normal T Cell Expressed And Secreted | - | Computer Acronyms(common) |
| RAO | Remedial Action Objective | - | Computer Acronyms(common) |
| RAP | Receptor-associated Protein | - | Computer Acronyms(common) |
| RAP | Remedial Action Project Or Plan | - | Computer Acronyms(common) |
| RAPD | Randomly Amplified Polymorphic DNA | - | Computer Acronyms(common) |
| RAPID | Ruggedized Advanced Pathogen Identification Device | - | Computer Acronyms(common) |
| RAPIDS | Regional Air Pollutant Inventory Development System | - | Computer Acronyms(common) |
| RAPJ | Rotating Arc Plasma Jet | - | Computer Acronyms(common) |
| RAPRA | Rubber And Plastics Research Association | - | Computer Acronyms(common) |
| RAPS | Regional Air Pollution Study | - | Computer Acronyms(common) |
| RAPW | Relativistic Augmented Plane Wave | - | Computer Acronyms(common) |
| RAR | Retinoic Acid Receptor | - | Computer Acronyms(common) |
| RARE | Rapid Acquisition Relaxation-enhanced | - | Computer Acronyms(common) |
| RARE | Retinoic Acid-response Element | - | Computer Acronyms(common) |
| RAS | Reflectance Anisotropy Spectroscopy | - | Computer Acronyms(common) |
| RAS | Reflection-absorption Spectroscopy | - | Computer Acronyms(common) |
| RAS | Renin-angiotensin System | - | Computer Acronyms(common) |
| RAS | Restricted Active Space (wave Function) | - | Computer Acronyms(common) |
| RAS | Returned Activated Sludge | - | Computer Acronyms(common) |
| RAS | Routine Analytical Services | - | Computer Acronyms(common) |
| RASA | Regional Aquifer Systems Analysis (program Of USGS) | - | Computer Acronyms(common) |
| RASS | Ratio Acoustic Sounding System | - | Computer Acronyms(common) |
| RASSCF | Restricted Active Space SCF | - | Computer Acronyms(common) |
| RASSI | Restricted Active Space State Interaction | - | Computer Acronyms(common) |
| RAST | Radioallergosorbent Test (immunoassay) | - | Computer Acronyms(common) |
| RASW | Relativistic Augmented Spherical Wave Method | - | Computer Acronyms(common) |
| RATL | Risk Analysis Testing Laboratory | - | Computer Acronyms(common) |
| RATM | Renormalized Average T-matrix (for D.-of-states Calcns.) | - | Computer Acronyms(common) |
| RB | Renormalized Band (method In Electronic-structure Calcns.) | - | Computer Acronyms(common) |
| RBA | Refined Born Approximation (for Atom-mol. Collisions) | - | Computer Acronyms(common) |
| RBAO | Reaction-bonded Aluminum Oxide | - | Computer Acronyms(common) |
| RBC | Red Blood Cell | - | Computer Acronyms(common) |
| RBC | Rotating Biological Contactor | - | Computer Acronyms(common) |
| RBCA | Risk-based Corrective Action | - | Computer Acronyms(common) |
| RBCOD | Readily Biodegradable Chemical Oxygen Demand | - | Computer Acronyms(common) |
| RBCODUR | Readily Biodegradable Chemical Oxygen Demand Uptake Rate | - | Computer Acronyms(common) |
| RBE | Relative Biological Effectiveness | - | Computer Acronyms(common) |
| RBF | Radial Basis Function | - | Computer Acronyms(common) |
| RBF | Renal Blood Flow | - | Computer Acronyms(common) |
| RBL | Rat Basophilic Leukemia | - | Computer Acronyms(common) |
| RBM | Radial Breathing Mode | - | Computer Acronyms(common) |
| RBM | Random Bonding Model | - | Computer Acronyms(common) |
| RBM | Rigid Band Model | - | Computer Acronyms(common) |
| RBOT | Rotary Bomb Oxidn. Test | - | Computer Acronyms(common) |
| RBP | Retinol Binding Protein | - | Computer Acronyms(common) |
| RBR | Reductive Burning Recovery | - | Computer Acronyms(common) |
| RBS | Rutherford Backscattering | - | Computer Acronyms(common) |
| RBS | Rutherford Backscattering Spectrometry | - | Computer Acronyms(common) |
| RBS | Ribosome Binding Site | - | Computer Acronyms(common) |
| RBSC | Reaction-bonded Silicon Carbide | - | Computer Acronyms(common) |
| RBSN | Reaction-bonded Silicon Nitride | - | Computer Acronyms(common) |
| RC(XI) | (fully) Correlated Relativistic Local-density | - | Computer Acronyms(common) |
| RCA | Ricinus Communis Agglutinin | - | Computer Acronyms(common) |
| RCA | Rolling-circle Amplification | - | Computer Acronyms(common) |
| RCC | Relativistic Coupled Cluster | - | Computer Acronyms(common) |
