| PSCL | Propellant Systems Cleaning Laboratory | In English | → Research institutes → Spaceflight engineering, astronautics |
| PSCU | Power Supply Control Unit | In English | → Energy economics → Electrical engineering |
| PSD | Power Spectral Density | In English | → Energy economics → Electrical engineering |
| PSD | Power Systems Division | In English | → Energy economics → Electrical engineering |
| PSDF | Propulsion System Development Facility | In English | → Vehicle engineering |
| PSDU | Power and Signal Distribution Unit | In English | → Energy economics → Electrical engineering → Telecommunications |
| PSEPR | Pôle Système Électrique Production Régionale | In French | → Electrical engineering |
| PSF | Probability of Stress Failure | In English | → Mechanical engineering |
| PSF | Propellant Servicing Facility | In English | → Spaceflight engineering, astronautics |
| PSG | Power Subsystem Group | In English | → Energy economics → Electrical engineering |
| PSI | Power Static Inverter | In English | → Energy economics |
| PSIG | Propulsion Systems Integration Group | In English | → Spaceflight engineering, astronautics |
| PSIU | Power and Signal Interface Unit | In English | → Energy economics → Electrical engineering → Telecommunications |
| PSM | Power Storage Module | In English | → Energy economics |
| PSM | Propellant Storage Module | In English | → Spaceflight engineering, astronautics |
| PSMI | Pryde Schropp McComb, Inc (www.psmi.ca) | In English | → Civil engineering → Transport and postal services |
| PSO | Polskie Składy Oponiarskie | In Polish | → Automobile manufacturing |
| PSP | Planetary Scan Platform | In English | → Spaceflight engineering, astronautics |
| PSP | Planetary Scan Probe | In English | → Spaceflight engineering, astronautics |
| PSPA | Pilotage des Systèmes de Production Automatisée | In French | → Mechanical engineering |
| PSS | Propellant Supply Subsystem | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| PSS | Propulsion Subsystem | In English | → Vehicle engineering |
| PSS | Propulsion Support System | In English | → Vehicle engineering |
| PSS | Procédé de Stabilisation et Solidification | In French | → Environmental technology, water supply, waste management |
| PSTL | Pressure Model Static and Transient Launch Configuration | In English | → Spaceflight engineering, astronautics |
| PSU | Power Switching Unit | In English | → Energy economics → Electrical engineering |
| PSV | Probability of Vehicle Success | In English | → Spaceflight engineering, astronautics |
| PSV | Planetary Space Vehicle | In English | → Spaceflight engineering, astronautics |
| PT | Propulsion Test | In English | → Vehicle engineering |
| PT | Power Transfer | In English | → Energy economics |
| PTA | Propulsion Test Article | In English | → Vehicle engineering |
| PTAN | Preschool Technical Assistance Network | In English | → Education |
| PTB | Physikalisch-Technische Bundesanstalt | In German | → Physics |
| PTCC | Propulsion Test Control Center | In English | → Spaceflight engineering, astronautics |
| PTCS | Propellant Tanking Computer System | In English | → Spaceflight engineering, astronautics |
| PTD | Provisioning Technical Documentation | In English | |
| PTD | Preliminary Technical Directive | In English | |
| PTE | Plate-forme Technologique Européenne | In English | |
| PTO | Power Test Operation | In English | → Energy economics |
| PTR | Program Technical Review | In English | → Management |
| PTR | Projektträger Reaktorsicherheitsforschung | In German | → Nuclear technology |
| PTR | Prestation Technologique Réseau | In French | |
| PTS | Payload Transportation System | In English | → Vehicle engineering |
| PTV | Pathfinder Test Vehicle | In English | → Spaceflight engineering, astronautics |
| PU | Propellant Utilization | In English | → Spaceflight engineering, astronautics |
| PU | Propellant Unit | In English | → Spaceflight engineering, astronautics |
| PU | Power Unit | In English | → Energy economics → Electrical engineering |
| PUCE | Programme pour l'Utilisation des Composants Électroniques | In French | → 621038 |
| PUCS | Propellant Utilization Control System | In English | → Spaceflight engineering, astronautics |
| PUGS | Propellant Utilization and Gauging System | In English | → Spaceflight engineering, astronautics |
| PUMA | Programme pour l'Utilisation des Matériaux Avancés | In French | |
| PUV | Propellant Utilization Valve | In English | → Spaceflight engineering, astronautics |
| PV | Photovoltaic | In English | → Energy economics |
| PVA | Propellant Valve Actuator | In English | → Spaceflight engineering, astronautics |
| PVA | Preburner Valve Actuator | In English | → Spaceflight engineering, astronautics |
| PVDS | Propellant Vent and Drain System | In English | → Spaceflight engineering, astronautics |
| PVED | Propulsion And Vehicle Engineering Division | In English | → Vehicle engineering |
| PVO | Pioneer Venus Orbiter | In English | → Astronomy → Spaceflight engineering, astronautics |
| PVR | Precision Voltage Reference | In English | → Electrical engineering |
| PVT | Pyrotechnic Verification Test | In English | → Spaceflight engineering, astronautics |
| PVT | Preflight Verification Test | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| PVTCS | Photovoltaic Thermal Control System | In English | → Energy economics |
| PWA | Printed Wiring Assembly | In English | → Electronics |
| PWA | Pratt and Whitney Aircraft | In English | → Aeronautics, aircraft |
| PWB | Printed Wiring Board | In English | → Electronics |
| PWDS | Protected Wire Distribution System | In English | → Electrical engineering |
| PWGSC | Public Works and Government Services Canada (www.tpsgc-pwgsc.gc.ca) = TPSGC | Travaux Publics et Services Gouvernementaux Canada | In French |
In English | → Central administration → Civil engineering |
| PWMD | Printed Wiring Master Drawing | In English | → Electronics |
| PWR | Pressurized Water Reactor = REP | Réacteur à Eau Pressurisée | In French = DWR | Druckwasserreaktor | In German |
In English | → Nuclear technology |
| PWR | Politechnika Wrocławska | In Polish | → Specialized or (poly)technical colleges |
| PWT | Propulsion Wind Tunnel | In English | → Vehicle engineering |
| QCM | Quartz Crystal Microbalance | In English | → Electronics |
| Qe2 | Quantock Energy & Environment | In English | → Energy economics |
| QFP | Quad Flat Pack | In English | → Electronics |
| QJMAM | Quarterly Journal of Mechanics and Applied Mathematics | In English | → Serial publications, periodicals → Mathematics → Mechanical engineering |
| QMS | Qualification Model Spacecraft | In English | → Spaceflight engineering, astronautics |
| QRSL | Quick-Reaction Space Laboratory | In English | → Research institutes → Spaceflight engineering, astronautics |
| QT | Qualification Test | In English | |
| QTP | Qualification Test Procedure | In English | |
| QTP | Qualification Test Plan | In English | |
| QTR | Qualification Test Report | In English | |
| QTV | Qualification Test Vehicle | In English | → Spaceflight engineering, astronautics |
| QVT | Qualified Verification Testing | In English | |
| R&D | Research and Development = R&D | Recherche et développement | In French = F&E | Forschung und Entwicklung | In German = I+D | Investigación y Desarrollo | In Spanish = R&S | Ricerca e Sviluppo | In Italian = P&D | Pesquisa e Desenvolvimento | In Portuguese = O&O | Onderzoek en Ontwikkeling | In Dutch = FoU | Forsøk og Utvikling | In Norwegian |
In English | → Research policy |
| R&D | Recherche et développement = F&E, I+D, R&S, P&D, O&O, FoU (look above) |
In French | → Research policy |
| R&DO | Research and Development Operations | In English | → Research policy |
| R&E | Research and Engineering | In English | → Research policy |
| R&S | Ricerca e Sviluppo = R&D, F&E, I+D, P&D, O&O, FoU (look above) |
In Italian | → Research policy |
| R&T | Research and Technology | In English | → Research policy |
| R2I | Réseau Industriel d'Innovation | In French | → Research policy → Industry, industrial policy |
| RAD | Research and Advanced Development | In English | → Research policy |
| RAE | Royal Aerospace Establishment | In English | → Aeronautics, aircraft → Spaceflight engineering, 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 | Réseau d’Alimentation Générale | In French | → Electrical engineering |
| RAI | Radar Altimeter Indicator | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RAID | Regional Association for Irrigation and Drainage = ARID | Association Régionale pour l'Irrigation et le Drainage | In French |
In English | → Associations → 627 → Agricultural sciences |
| RALPH | Reduction and Acquisition Of Lunar Pulse Heights | In English | → Astronomy → Spaceflight engineering, astronautics |
| RALT | Radar Altimeter | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RANN | Research Applied to National Needs | In English | → Research policy |
| RAPCON | Radar Approach and Control | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RASM | Remote Analog Submultiplexer | In English | → Electrical engineering |
| RATCC | Radar Air Traffic Control Center | In English | → Aeronautics, aircraft |
| RATO | Rocket-Assisted Takeoff | In English | → Spaceflight engineering, astronautics |
| RAWS | Role-Adaptable Weapons System | In English | → Military engineering |
| RC | Resistance-Capacitance | In English | → Electrical engineering |
| RCB | Remote Circuit Breaker | In English | → Electrical engineering |
| RCC | Rough Combustion Cutoff | In English | → Vehicle engineering |
| RCCA | Rough Combustion Cutoff Assembly | In English | → Vehicle engineering |
| RCCB | Remote Central Circuit Breaker | In English | → Electrical engineering |
| RCD | Réacteur Complétement Déchargé | In French | → Nuclear technology |
| RCO | Radio Comptoir de l'Ouest (www.rco.fr) | In French | → Telecommunications → Electronics |
| RCS | Reentry Control System | In English | → Spaceflight engineering, astronautics |
| RDS | Rocketdyne Digital Simulator | In English | → Spaceflight engineering, astronautics |
| RDT | Réseau de Développement Technologique | In French | |
| RDTC | Réseau de Développement Technologique Corse | In French | |
| RE | Responsible Engineer | In English | |
| REA | Rocket Engine Assembly | In English | → Spaceflight engineering, astronautics |
| REACM | Regional Energy Agency of Central Macedonia | In English | → Energy economics |
| REAM | Rocket Engine Assembly Module | In English | → Spaceflight engineering, 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 | → Electrical engineering |
| RECIFE | REcherche sur la Capacité des Infrastructures FErroviaires | In French | → Rail transport engineering → Transport and postal services |
| REDAC | Rockwell Electronic Design Analysis Code | In English | → Electronics |
| REDB | Rockwell Engineering Data Base | In English | |
| 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 |
| 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 |
| REM | Rocket Engine Module | In English | → Spaceflight engineering, astronautics |
| RENAEL | Rete Nazionale Agenzie Energetiche Locali | In Italian | → Energy economics |
| RENAISSANCE | Renewable ENergy Acting in SuStainable And Novel Community Enterprises | In English | → Energy economics |
| RENATER | Réseau National de Télécommunication pour la Technologie, l'Enseignement et la Recherche | In French | → Research policy → Networks, communication → Education |
| ReNEv | Research in Nondestructive Evaluation | In English | → Serial publications, periodicals |
| REP | Réacteur à Eau Pressurisée = PWR, DWR (look above) |
In French | → Nuclear technology |
| RESC | Réacteur à Eau SuperCritique | In French | → Nuclear technology |
| RESTART | Renewable Energy Strategies and Technology Applications for Regenerating Towns | In English | → Energy economics |
| RET | Régie d'Electricité de Thônes | In French | → Electrical engineering |
| RETS | Reconfigurable Electrical Test Stand | In English | → Electrical engineering |
| REU | Remote Electronics Unit | In English | → Electronics |
| REUS | Rational Energy Use & Solutions | In English | → Energy economics |
| REVS | Requirements Engineering and Validation System | In English | |
| RFECP | Request For Engineering Change Proposal | In English | |
| RFEI | Request For Engineering Information | In English | |
| RFHA | Reusable Flight Hardware Authorization | In English | → Hardware → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RFI | Rete Ferroviaria Italiana | In Italian | → Rail transport engineering → Transport and postal services |
| RFrM | Revue Francaise de Mécanique | In French | → Serial publications, periodicals → Mechanical engineering |
| RFT | Rat für Forschung und Technologieentwicklung (www.rat-fte.at) | In German | → Research policy |
| RFT | Rat für Forschung und Technologie | In German | → Research policy |
| RGC | Rénovation Générale de Cuves | In French | → Mechanical engineering |
| RGC&U | Réseau Génie Civil et Urbain | In French | → Civil engineering → Building |
| RGN | Revue Générale Nucléaire | In French | → Serial publications, periodicals → Nuclear, atomic, and molecular physics → Nuclear technology |
| RIC | Resistance, Inductance, and Capacitance | In English | → Physics → Electrical engineering |
| RIDITT | Rete Italiana per la Diffusione dell'Innovazione e il Trasferimento Tecnologico alle Imprese | In Italian | |
| RIE | Reactive Ion Etching | In English | |
| RIIC | Research Institute for Integrated Circuits | In English | → Electronics |
| RILEM | Réunion Internationale des Laboratoires pour l'Essai des Matériaux | In French | → Organizations and associations → Research institutes → Materials science |
| RIMSS | Rockwell International Modular Satellite System | In English | → Spaceflight engineering, astronautics |
| RIN | Royal Institute of Navigation | In English | → Geodesy, cartography → Vehicle engineering → Transport and postal services |
| RIO | Ressourcenverbrauch reduzieren, Innovationen implementieren, Output optimieren | In German | → Nature |
| RISEC | Rockwell International Shuttle Equipment Cradle | In English | → Spaceflight engineering, astronautics |
| RITEAU | Réseau 'Eau et Technologies de l'environnement' | In French | → Nature → Environmental technology, water supply, waste management |
| RJ/EC | Reaction Jet/Engine Control | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RJC | Reaction Jet Control | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RJD | Reaction Jet Driver | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RJD | Reaction Jet Device | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RJDA | Reaction Jet Driver Aft | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RJDF | Reaction Jet Driver Forward | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RJOD | Reaction Jet/OMS Driver | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RKA | Rossiskoye Kosmicheskoye Agentsvo | In Russian | → Spaceflight engineering, astronautics |
| RLEMR | Research Laboratory Engineering Materials Report | In English | → Serial publications, periodicals |
| RLPME | Research Laboratory Precision Machinery Electronics Bulletin | In English | → Serial publications, periodicals → Mechanical engineering → Electronics |
| RM | Rendezvous Maneuver | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RMetA | Rivista di Meteorologia Aeronautica | In Italian | → Serial publications, periodicals → Meteorology, climatology → Aeronautics, aircraft |
| RMN | Ressonància Magnètica Nuclear = RMN | Résonance Magnétique Nucléaire | In French = NMR | Nuclear Magnetic Resonance | In English = RMN | Risonanza Magnetica Nucleare | In Italian = תמ"ג | תהודה מגנטית גרעינית | In Hebrew = ЯМР | Я́дерного магни́тного резона́нса | In Russian = НМР | Нуклеарна магнетна резонанција | In Serbian |
In Catalan | → Medicine → Nuclear, atomic, and molecular physics → 629031 |
| RMN | Risonanza Magnetica Nucleare = NMR, תמ"ג, ЯМР, НМР (look above) |
In Italian | → Medicine → Nuclear, atomic, and molecular physics → 629031 |
| RMN | Résonance Magnétique Nucléaire = NMR, תמ"ג, ЯМР, НМР (look above) |
In French | → Medicine → Nuclear, atomic, and molecular physics → 629031 |
| RMNT | Réseau Micro et Nanotechnologies | In French | |
| RNDE | Réseau National des Données sur l'Eau | In French | → Organizations and associations → Hydrology → Environmental technology, water supply, waste management |
| RNEP | Robust Nuclear Earth Penetrator | In English | → Nuclear technology → Military engineering |
| RNPP | Reliability and Network Planning Panel | In English | → 6208 |
| RNR | éacteur Nucléaire Rapide | In French | → Nuclear technology |
| RNR | Réacteur à Neutrons Rapides | In French | → Nuclear technology |
| RNS | Reusable Nuclear Stage | In English | → Nuclear technology |
| ROCES | Ranger Orbiter Crew Escape System | In English | → Spaceflight engineering, astronautics |
| ROEU | Remotely Operated Electrical Umbilical | In English | → Spaceflight engineering, astronautics |
| RoHS | Restriction of the use of certain Hazardous Substances (in electrical and electronic equipment) | In English | → Chemicals → Electrical engineering → Electronics |
| RORSAT | Radar Ocean Reconnaissance Satellite | In English | → Marine research, oceanography → Spaceflight engineering, astronautics |
| ROSA | Romanian Space Agency | In English | → Astronomy → Spaceflight engineering, astronautics |
| ROSAT | ROentgen SATellite | In English | → Astronomy → Spaceflight engineering, astronautics |
| ROTV | Returnable Orbital Transfer Vehicle | In English | → Spaceflight engineering, astronautics |
| RP | Rocket Propellant | In English | → Spaceflight engineering, astronautics |
| RPC | Remote Power Controller | In English | → Electrical engineering |
| RPC | Remote Power Control | In English | → Electrical engineering |
| RPDE | Réseau Partenarial des Données sur l'Eau | In French | → Organizations and associations → Hydrology → Environmental technology, water supply, waste management |
| RPL | Rated Power Level | In English | → Electrical engineering |
|