| Acronym | Sense | Language | Topics | 
|---|---|---|---|
| RA | Rheumatoide Arthritis | In German | → Pathology | 
| RAADIS | Réseau pour une Agriculture et une Alimentation Durables Inventives et Solidaires | In French | → Organizations and associations → Agricultural sciences → Food technology  | 
| RAAP | Red Académica Peruana | In Spanish | → Computer science → Higher education, universities → Telecommunications  | 
| RAAS | Renine, Angiotensine, Aldosteron Systeem | In Dutch | → Blood and circulatory system → Cardiology  | 
| RABF | Radio Astronomy Bandstop Filter | In English | → Astronomy → Telecommunications  | 
| RACC | Radio Advertising Clearance Centre | In English | → Telecommunications → 659  | 
| RACES | Radio Amateur Civil Emergency Service | In English | → Telecommunications | 
| RACH | Random Access Channel | In English | → Telecommunications | 
| RAD | Research and Advanced Development | In English | → Research policy → Engineering, technology  | 
| RADAR | RAdio Detection And Ranging | In English | → Telecommunications | 
| RADIUS | Remote Authentication Dial In User Service | In English | → Networks, communication → Telecommunications  | 
| RADO | Radiation Dosimetry | In English | → Radioactivity → Astronautics → Astronomy  | 
| RADO-HTR | Radiation Dosimetry - High Temperature Ratio | In English | → Radioactivity → Astronautics → Astronomy  | 
| RAE | Royal Aerospace Establishment | In English | → Aeronautics, aircraft → Astronautics  | 
| RaEE | Radio and Electronic Engineer | In English | → Serial publications, periodicals → Telecommunications → Electronics  | 
| RAéS | Réseau Recherche Aéronautique sur le Supersonique | In French | → Aeronautics, aircraft | 
| RAG | Rohöl-Aufsuchungs Aktiengesellschaft (https://www.rag-austria.at/) | In German | → Chemical technology → Austria  | 
| RAG | Réseau d'Alimentation Générale | In French | → Energy economics → France  | 
| RAGIE | Red Avanzada Guatemalteca para la Investigación y Educación | In Spanish | → Computer science → Education → Mathematics and natural sciences → Telecommunications  | 
| RAI | Radio Audizioni Italiane (www.rai.it) | In Italian | → Telecommunications → Italia  | 
| RAI | Radar Altimeter Indicator | In English | → Aeronautics, aircraft → Astronautics  | 
| RAI | Roll Attitude Indicator | In English | → Astronautics | 
| RAI | Radiotelevisione Italiana (www.rai.it) | In Italian | → Telecommunications → Italia  | 
| RAI | Rijwiel en Automobiel Industrie | In Dutch | → Automobile manufacturing | 
| RAI | Résultat Avant Impôt | In French | → Accounting → Taxes, duties  | 
| RAICES | Red Avanzada de Investigación, Ciencia y Educación Salvadoreña | In Spanish | → Computer science → Education → Mathematics and natural sciences → Telecommunications  | 
| RAID | Regional Association for Irrigation and Drainage = ARID | Association Régionale pour l'Irrigation et le Drainage | In French  | 
In English | → Associations → 627 → Agricultural sciences  | 
| RAISIN | Réseau d'Alerte, d'Investigation et de Surveillance des Infections Nosocomiales | In French | → Organizations and associations → Infectious diseases  | 
| RAISOM | Réseaux de collecte IP Sans Fil Optimisés | In French | → Networks, communication → Telecommunications  | 
| RALPH | Reduction and Acquisition Of Lunar Pulse Heights | In English | → Astronomy → Astronautics  | 
| RALT | Radar Altimeter | In English | → Aeronautics, aircraft → Astronautics  | 
| RAMAC | Random Access Method of Accounting And Control | In English | → Accounting | 
| RAMC | Régime Canadien d'Accès aux Médicaments = CAMR | Canada's Access to Medicines Regime | In English  | 
In French | → Pharmacology, toxicology → Canada  | 
| RAN | Report À Nouveau | In French | → Accounting | 
| RANN | Research Applied to National Needs | In English | → Research policy → Engineering, technology  | 
| RAP | Reserve Auxiliary Payload | In English | → Astronautics | 
| RAP | Responsibility Accounting Program | In English | → Accounting | 
| RAP | Reprise des Amortissements et Provisions | In French | → Accounting | 
| RAPCON | Radar Approach and Control | In English | → Aeronautics, aircraft → Astronautics  | 
| RAPHAEL | ReActor for Process heat, Hydrogen And ELectricity generation | In English | → Energy economics | 
| RAPID | Revolutionary Avalanche Photodiode Infrared Detector | In English | → Electronics → Tourism  | 
| RAQPA | Résidence d'Accueil de Quartier pour Personnes Agées | In French | → Accommodation → Gerontology  | 
| RARE | Réseau de recherche et d'innovation technologique 'Alimentation Référence Europe' | In French | → Nutrition → Food technology  | 
| RaRLJ | Radio Research Laboratories Journal | In English | → Serial publications, periodicals → Telecommunications  | 
| RaRLR | Radio Research Laboratories Review | In English | → Serial publications, periodicals → Telecommunications  | 
| RAS | Requirements Accounting System | In English | → Accounting | 
| RAS | Remontée Aéro-Souterraine | In French | → Energy economics → Electrical engineering  | 
| RaSc | Radio Science | In English | → Serial publications, periodicals → Telecommunications  | 
| RaScB | Radio Science Bulletin | In English | → Serial publications, periodicals → Telecommunications  | 
| RaScS | Radio Science Supplement | In English | → Serial publications, periodicals → Telecommunications  | 
| RASM | Remote Analog Submultiplexer | In English | → Electrical engineering | 
| RASMUS | Remote Accessible Software configurable Multi-channel Ultrasound Sampling system | In English | → Software → Diagnostics  | 
| RASTI | Rapid Speech Transmission Index | In English | → Acoustical engineering | 
| RATCC | Radar Air Traffic Control Center | In English | → Aeronautics, aircraft | 
| RATO | Rocket-Assisted Takeoff | In English | → Astronautics | 
| RATP | Régie Autonome des Transports Parisiens (www.ratp.fr) | In French | → Transport and postal services → France  | 
| RATP | Réseau pour l'Abolition des Transports Payants | In French | → Organizations and associations → Transport and postal services  | 
| RAU | Red Académica Uruguaya | In Spanish | → Computer science → Higher education, universities → Telecommunications  | 
| RAV | Reste À Ventiler | In French | → Accounting | 
| RAVeL | Réseau Autonome des Voies Lentes | In French | → Transport and postal services | 
| RAWS | Role-Adaptable Weapons System | In English | → Military engineering | 
| RBB | Rundfunk Berlin-Brandenburg | In German | → Telecommunications | 
| RBC | Red Blood Cells | In English | → Blood and circulatory system | 
| RBE | Relative Biological Effectiveness | In English | → Pharmacology, toxicology → Nuclear technology  | 
| RBF | Regional Blood Flow | In English | → Blood and circulatory system | 
| RBS | Radar Bomb Scoring | In English | → Military engineering | 
| RC | Reinforced Concrete | In English | → Construction | 
| RC | Resistance-Capacitance | In English | → Electrical engineering | 
| RCA | Radio Corporation of America | In English | → Telecommunications → United States  | 
| RCA | Responsabilité Civile Accident | In French | → Insurance → Accidents, risks, safety  | 
| RCAI | Résultat Courant avant Impôt | In French | → Accounting → Taxes, duties  | 
| RCB | Remote Circuit Breaker | In English | → Electrical engineering | 
| RCC | Rough Combustion Cutoff | In English | → Vehicle engineering | 
| RCC-C | Règles de Conception et de Construction des Assemblages de Combustible des Centrales Nucléaires | In French | → Nuclear technology | 
| RCC-E | Règles de Conception et de Construction des Matériels Électriques des Centrales Nucléaires | In French | → Nuclear technology | 
| RCC-G | Règles de Conception et de Construction du Génie Civil des Îlots Nucléaires REP | In French | → Nuclear technology | 
| RCC-M | Règles de Conception et de Construction des Matériels Mécaniques des Îlots Nucléaires REP | In French | → Nuclear technology | 
| RCC-MR | Règles de Conception et de Construction des Matériels Mécaniques des Îlots Nucléaires RNR | In French | → Nuclear technology | 
| RCCA | Rough Combustion Cutoff Assembly | In English | → Vehicle engineering | 
| RCCB | Remote Central Circuit Breaker | In English | → Electrical engineering | 
| RCCP | Recorder and Communications Control Panel | In English | → Telecommunications | 
| RCD | Réacteur Complétement Déchargé | In French | → Nuclear technology | 
| RCDD | Registered Communications Distribution Designer | In English | → Telecommunications | 
| RCF | Radios Chrétiennes en France | In French | → Organizations and associations → Telecommunications → Christianity → France  | 
| RCM | Reciprocating Chemical Muscle | In English | → Mechanical engineering → Chemical technology  | 
| RCN | Rockwell Communication Network | In English | → Telecommunications | 
| RCO | Radio Comptoir de l'Ouest | In French | → Trade → Electronics  | 
| RCP | Réanimation cardiopulmonaire | In French | → Traumatology | 
| RCP | Résumé des Caractéristiques du Produit = SPC | Summary of Product Characteristics | In English  | 
In French | → Pharmacology, toxicology | 
| RCP | RCP : Réanimation Cardio-Pulmonaire | In French | → Cardiology → Traumatology  | 
| RCP | Reação em Cadeia da Polimerase = PCR | Polymerase Chain Reaction | In English = ACP | Amplification en Chaîne par Polymérase | In French = TAN | Test d'amplification des Acides Nucléiques | In French = ПЦР | Полимера́зная Цепна́я Реа́кция | In Russian = PĈR | Polimeraza Ĉen-Reakcio | In Esperanto = PZR | Polimeraz Zəncir Reaksiyası | In Azerbaijani = ՊՇՌ | Պոլիմերազային շղթայական ռեակցիան | In Armenian = PGR | Polimerazinė Grandininė Reakcija | In Lithuanian = ПГУ | Полимеразын Гинжин Урвал | In Mongolian = ПЛР | Полімеразна Ланцюгова Реакція | In Ukrainian  | 
In Portuguese | → Biotechnology → Genetics → Enzymes  | 
| RCS | Reentry Control System | In English | → Astronautics | 
| RCS | Roux-Combaluzier-Schindler | In French | → Mechanical engineering | 
| RCSO-TIC | Réseau de Compétences de Suisse Occidentale en Technologie de l'Information et de la Communication | In French | → Computer science → Telecommunications → Switzerland  | 
| RCVS | Royal College of Veterinary Surgeons (www.rcvs.org.uk) | In English | → Organizations and associations → Veterinary medicine → United Kingdom  | 
| RD | Rétinopathie Diabétique | In French | → Pathology → Ophthalmology  | 
| RD | Route Départementale | In French | → Civil engineering and land transport → Transport and postal services  | 
| RDA | Recommended Dietary Allowances | 
In English | → Personal health and hygiene | 
| RDA | Recommended Daily Allowance = ADH | Aanbevolen Dagelijkse Hoeveelheid | In Dutch = ADI | Acceptabel Daglig Indtagelse | In Danish = RDI | Rekommenderat Dagligt Intag | In Swedish = ANC | Apports Nutritionnels Conseillés | In French  | 
In English | → Nutrition | 
| RDC | Rez-De-Chaussée | In French | → Accommodation → Construction  | 
| RDF | Radio Direction Finding | In English | → Telecommunications | 
| RDF | Radio Direction Finder | In English | → Telecommunications | 
| RDF | Refuse-Derived Fuel | In English | → Chemicals | 
| RDI | Rekommenderat Dagligt Intag = RDA, ADH, ADI, ANC (look above)  | 
In Swedish | → Nutrition | 
| RDI | Radar Doppler à Impulsions | In French | → Engineering, technology | 
| RDM | Repeats Detection Method | In English | → Algorithms → Computer-based techniques → Biotechnology  | 
| RDO | Radio Dom Ostankino | In Russian | → Telecommunications | 
| RDR | Règlement de Développement Rural | In French | → Agricultural sciences → Regional planning  | 
| RDS | Rocketdyne Digital Simulator | In English | → Astronautics | 
| RDS | Radio Data Systeem | In English | → Telecommunications | 
| RDS-TMC | Radio Data System - Traffic Message Channel | In English | → Telecommunications → Transport and postal services  | 
| RDT | Réseau de Développement Technologique | In French | → Engineering, technology | 
| RDTC | Réseau de Développement Technologique Corse | In French | → Engineering, technology | 
| RDW | Rijks Dienst voor het Wegverkeer (www.rdw.nl) | In Dutch | → Central administration → Vehicle engineering → Netherlands  | 
| RDX | Cyclotrimethyleentrinitramine | In Dutch | → Chemicals | 
| RE | Reproductive Endocrinologist | In English | → Reproductive biology | 
| RE | Responsible Engineer | In English | → Engineering, technology | 
| REA | Rocket Engine Assembly | In English | → Astronautics | 
| ReAA | Recherches Aéronautiques et Aérospatiales | In French | → Serial publications, periodicals → Aeronautics, aircraft → Astronautics  | 
| REACCIUN | Red Académica de Centros de Investigación y Universidades Nacionales | In Spanish | → Computer science → Education → Telecommunications  | 
| REACH | Registration, Evaluation and Authorization of Chemicals | In English | → Chemicals | 
| REACM | Regional Energy Agency of Central Macedonia | In English | → Energy economics | 
| REAM | Rocket Engine Assembly Module | In English | → Astronautics | 
| REB | Réacteur à Eau Bouillante = BWR | Boiling Water Reactor | In English = SWR | Siedewasserreaktor | In German  | 
In French | → Nuclear technology | 
| REC | Regional Electricity Company | In English | → Energy economics → Electrical engineering  | 
| RECIFE | REcherche sur la Capacité des Infrastructures FErroviaires | In French | → Rail transport engineering → Rail transport → France  | 
| RECITS | Recueil des Eléments de Connaissances Interdisciplinaires sur les Transports et leur Sécurité | In French | → Transport and postal services | 
| REDAC | Rockwell Electronic Design Analysis Code | In English | → Electronics | 
| REDB | Rockwell Engineering Data Base | In English | → Engineering, technology | 
| RedCYT | Red Científica y Tecnológica | In Spanish | → Computer science → Mathematics and natural sciences → Telecommunications  | 
| RéDI | Réseau des Doctorants de l'INRETS | In French | → Organizations and associations → Higher education, universities → Transport and postal services  | 
| REEEP | Renewable Energy and Energy Efficiency Partnership | In English | → Energy economics | 
| REEP | Radio Engineering and Electronic Physics | In English | → Serial publications, periodicals → Telecommunications → Electronics  | 
| REFIDI | Résidus d'Épuration des Fumées d'Incinérateur de Déchets Industriels | In French | → Environmental technology, water supply, waste management | 
| REFIOM | Résidu de Fumée d'Incinération d'Ordures Ménagères | In French | → Environmental technology, water supply, waste management | 
| REFLEX | Randomised Evaluation oF Long-term Efficacy rituXimab | In English | → Pharmacology, toxicology | 
| REG | Régie des Eaux de Grenoble | In French | → Environmental technology, water supply, waste management | 
| REG | Résistances Électriques et Gazières | In French | → Electrical engineering | 
| REGBIE | Regional Bioenergy Initiatives around Europe | In English | → Energy economics | 
| REIO | Renewable Energy Information Office | In English | → Energy economics | 
| REKAM | (Stichting) Regionale Kabeltelevisie Midden-Holland (www.rekam.nl) | In Dutch | → Foundations → Telecommunications → Netherlands  | 
| REM | Rocket Engine Module | In English | → Astronautics | 
| REM | Roentgen Equivalent Man | In English | → Radioactivity → Medicine  | 
| REMPARE | RE-ingénierie des Merlons de Protection par composants Anthropiques REcyclés | In French | → Construction | 
| RENAEL | Rete Nazionale Agenzie Energetiche Locali | In Italian | → Energy economics | 
| RENAISSANCE | Renewable ENergy Acting in SuStainable And Novel Community Enterprises | In English | → Energy economics | 
| RENAR | Asociația de Acreditare din România (https://www.renar.ro) | In Romanian | → Associations → Diagnostics  | 
| RENATA | Red Nacional Académica de Tecnología Avanzada | In Spanish | → Computer science → Telecommunications  | 
| RENATER | Réseau National de Télécommunication pour la Technologie, l'Enseignement et la Recherche | In French | → Research policy → Networks, communication → Education → Engineering, technology  | 
| ReNEv | Research in Nondestructive Evaluation | In English | → Serial publications, periodicals → Engineering, technology  | 
| RENIA | Red Nicaragüense de Internet Avanzada | In Spanish | → Computer science → Telecommunications → Internet  | 
| REOM | Redevance sur Enlèvement des Ordures Ménagères | In French | → Taxes, duties → Environmental technology, water supply, waste management  | 
| REP | Réacteur à Eau Pressurisée = PWR | Pressurized Water Reactor | In English = DWR | Druckwasserreaktor | In German  | 
In French | → Nuclear technology | 
| REPOM | Réseau national de surveillance des ports maritimes | In French | → Transport and postal services | 
| RER | Réseau Express Régional | In French | → Rail transport engineering → Transport and postal services  | 
| RERC | Rehabilitation Engineering Research Center | In English | → Research institutes → Pathology  | 
| RESC | Réacteur à Eau SuperCritique | In French | → Nuclear technology | 
| ReSMA | Reparto Sperimentazioni di Meteorologia Aeronautica | In Italian | → Meteorology, climatology → Aeronautics, aircraft  | 
| RESPECT | Route Empruntée en Sécurité par le Piéton Enfant Confronté au Trafic | In French | → Transport and postal services | 
| RESSAC | Recherche Et Sauvetage par Système Autonome Coopérant | In English | → Transport and postal services | 
| RESTART | Renewable Energy Strategies and Technology Applications for Regenerating Towns | In English | → Energy economics | 
| RET | Régie d'Electricité de Thônes | In French | → Electrical engineering | 
| RET | Resolution Enhancement Technology | In English | → Peripheral devices → Graphic industries, printing, publishing  | 
| RET | Résistance Évaporative Thermique | In French | → Textile industry | 
| RET | Rotterdamse Electrische Tram | In Dutch | → Rail transport engineering → Transport and postal services → Netherlands  | 
| RETINA | Red TeleInformática Académica | In Spanish | → Computer science → Telecommunications  | 
| RETS | Reconfigurable Electrical Test Stand | In English | → Electrical engineering | 
| REU | Remote Electronics Unit | In English | → Electronics | 
| REUNA | Red Universitaria Nacional | In Spanish | → Computer science → Higher education, universities → Telecommunications  | 
| REUS | Rational Energy Use & Solutions | In English | → Energy economics | 
| REVS | Requirements Engineering and Validation System | In English | → Engineering, technology | 
| RF | Radio Frequency | In English | → Telecommunications | 
| RF | Risk Factor | In English | → Accidents, risks, safety | 
| RFDA | Radio Frequency Deployed Assembly | In English | → Telecommunications | 
| RFDA | Regional Food Distribution Association | In English | → Associations → Food technology  | 
| RFDU | Radio Frequency and Digital Unit | In English | → Computer science → Telecommunications  | 
| RFECP | Request For Engineering Change Proposal | In English | → Engineering, technology | 
| RFEI | Request For Engineering Information | In English | → Engineering, technology | 
| RFF | Réseau Ferré de France (www.rff.fr) | In French | → Transport and postal services → France  | 
| RFHA | Reusable Flight Hardware Authorization | In English | → Computer hardware → Aeronautics, aircraft → Astronautics  | 
| RFI | Radio France International (www.rfi.fr) | In French | → Telecommunications → France  | 
| RFI | Rete Ferroviaria Italiana | In Italian | → Rail transport engineering → Transport and postal services → Italia  | 
| RFI | Radio Frequency Interference | In English | → Telecommunications → Electronics  | 
| RFID | Radio Frequency Identification | In English | → Computer science → Telecommunications  | 
| RFLP | Restriction Fragment Length Polymorphism | In English | → Genetics → Biotechnology  | 
| RFrM | Revue Francaise de Mécanique | In French | → Serial publications, periodicals → Mechanical engineering → France  | 
| RFS | Règle Fondamentale de Sûreté | In French | → Nuclear technology | 
| RFT | Rat für Forschung und Technologie | In German | → Organizations and associations → Research policy → Engineering, technology  | 
| RFT | Rat für Forschung und Technologieentwicklung (https://www.rat-fte.at/) | In German | → Organizations and associations → Research policy → Engineering, technology → Austria  | 
| RFTK | Radio Frequency Tracking | In English | → Telecommunications | 
| RFTO | Renewable Transport Fuels Obligation | In English | → Transport and postal services | 
| RFTS | Radio Frequency Transmission System | In English | → Telecommunications | 
| RFU | Radio Frequency Unit | In English | → Telecommunications | 
| RFVL | Rotonde Ferroviaire de la Vallée du Loir | In French | → Rail transport engineering → Rail transport  | 
| RGA | Recensement Général de l'Agriculture | In French | → Agricultural sciences | 
| RGC | Rénovation Générale de Cuves | In French | → Mechanical engineering | 
| RGC | Roanoke Gas Company | In English | → Chemical technology | 
| RGC | Richard Glynn Consultants | In English | → Consulting | 
| RGC&U | Réseau Génie Civil et Urbain | In French | → Civil engineering → Construction  | 
| RGG | Réseau à Grand Gabarit | In French | → Transport and postal services |