| PSTL | Pressure Model Static and Transient Launch Configuration | In English | → Spaceflight engineering, astronautics |
| PSTN | Public Switched Telephone Network = RTCP | Réseau Téléphonique Commuté Public | In French = ТСОП | елефонная сеть общего пользования | In Russian |
In English | → Telecommunications |
| 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 | Power Transfer | In English | → Energy economics |
| PT | Propulsion Test | In English | → Vehicle engineering |
| PT | Post- og Teletilsynet | In Norwegian | → Telecommunications → Transport and postal services |
| PTA | Propulsion Test Article | In English | → Vehicle engineering |
| PTAN | Preschool Technical Assistance Network | In English | → Education → Engineering, technology |
| PTB | Physikalisch-Technische Bundesanstalt | In German | → Physics → Engineering, technology |
| PTC | Радио-телевизија Србије (www.rts.co.yu) = RTS | Radio Televizija Srbije | In Serbian |
In Serbian | → Telecommunications |
| PTC | Plasma Thromboplastin Component | In English | → Blood and circulatory system → Pharmacology, toxicology |
| PTCA | Percutaneous Coronary Transluminal Angioplasty | In English | → Cardiology |
| PTCC | Propulsion Test Control Center | In English | → Spaceflight engineering, astronautics |
| PTCR | Pad Terminal Connection Room | In English | → Telecommunications |
| PTCS | Propellant Tanking Computer System | In English | → Spaceflight engineering, astronautics |
| PTD | Preliminary Technical Directive | In English | → Engineering, technology |
| PTD | Provisioning Technical Documentation | In English | → Engineering, technology |
| PTE | Plate-forme Technologique Européenne | In English | → Engineering, technology |
| PTI | Purpura Thrombopénique Idiopathique | In French | → Pathology |
| PTN | Publika telefonnätet | In Swedish | → Telecommunications |
| PTO | Power Test Operation | In English | → Energy economics |
| PTP | Previously Treated Patient | In English | → Pharmacology, toxicology |
| PTR | Program Technical Review | In English | → Management → Engineering, technology |
| PTR | Projektträger Reaktorsicherheitsforschung | In German | → Nuclear technology |
| PTR | Prestation Technologique Réseau | In French | → Engineering, technology |
| PTS | Payload Transportation System | In English | → Vehicle engineering |
| PTT | Poŝto, Telegrafo kaj Telefono | In Esperanto | → Telecommunications → Transport and postal services |
| PTT | Post Telegraaf Telefoon | In Dutch | → Telecommunications → Transport and postal services |
| PTT | Purpura Thrombotique Thrombocytopénique | In French | → Blood and circulatory system → Pathology |
| PTV | Pathfinder Test Vehicle | In English | → Spaceflight engineering, astronautics |
| PU | Power Unit | In English | → Energy economics → Electrical engineering |
| PU | Propellant Unit | In English | → Spaceflight engineering, astronautics |
| PU | Propellant Utilization | In English | → Spaceflight engineering, astronautics |
| PUCA | Plan Urbanisme, Construction, Architecture | In French | → Building → Architecture |
| 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 | → Engineering, technology |
| PUP | Previously Untreated Patient | In English | → Pharmacology, toxicology |
| PUV | Propellant Utilization Valve | In English | → Spaceflight engineering, astronautics |
| PV | Polyglobulie de Vaquez | In French | → Blood and circulatory system → Pathology |
| PV | Photovoltaic | In English | → Energy economics |
| PVA | Plasma Viro-Atténué | In French | → Blood and circulatory system |
| PVA | Preburner Valve Actuator | In English | → Spaceflight engineering, astronautics |
| PVA | Propellant Valve Actuator | In English | → Spaceflight engineering, astronautics |
| PVC | Permanent Virtual Circuit | In English | → Telecommunications |
| PVC | Polyvinyl Chloride | In English | → 665 |
| PVDC | Polyvinylidene Chloride | In English | → Plastic industry |
| PVDF | Polyvinylidenefluoride | In English | → Plastic industry → Chemicals → Chemistry |
| PVDS | Propellant Vent and Drain System | In English | → Spaceflight engineering, astronautics |
| PVED | Propulsion And Vehicle Engineering Division | In English | → Vehicle engineering |
| PVL | Periventrikuläre Leukomalazie = PVL | Periventricular Leukomalacia | In English = PVL | Periventriculaire Leukomalacie | In Dutch = LMPV | Leucomalacie périventriculaire | In French |
In German | → Obstetrics → Neurology |
| PVL | Periventricular Leukomalacia = LMPV (look above) |
In English | → Obstetrics → Neurology |
| PVL | Periventriculaire Leukomalacie = LMPV (look above) |
In Dutch | → Obstetrics → Neurology |
| PVO | Pioneer Venus Orbiter | In English | → Astronomy → Spaceflight engineering, astronautics |
| PVO | Pasaules veselības organizācija = MOS | Monda Organiz(aĵ)o pri Sano | In Esperanto = WHO | World Health Organization | In English = OMS | Organisation Mondiale de la Santé | In Esperanto = OMS | Organizzazione Mondiale della Sanità | In Italian = WGO | Wêreldgesondheidsorganisasie | In Afrikaans = OMS | Organización Mundial de la Salú | In Asturian = СЗО | Световната здравна огранизация | In Bulgarian = SZO | Světová zdravotnická organizace | In Czech = OMS | Organització Mundial de la Salut | In Catalan = OMS | Organización Mundial de la Salud | In Spanish = MTO | Maailma Terviseorganisatsioon | In Estonian = MOE | Munduko Osasun Erakundea | In Basque = OMS | Organisacion mondiâla de la sandât | FRP = OMS | Organización Mundial da Saúde | In Galician = SZO | Svjetska zdravstvena organizacija | In Croatian = RTD | Rêxistina Tendurustiyê ya Dinyayê | In Kurdish = UMS | Urganizazziun mundiala da la Santaa | In Lombard = PSO | Pasaulio sveikatos organizacija | In Lithuanian |
In Latvian | → United Nations → Medicine |
| 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 | Pratt and Whitney Aircraft | In English | → Aeronautics, aircraft |
| PWA | Printed Wiring Assembly | In English | → Electronics |
| PWB | Printed Wiring Board | In English | → Electronics |
| PWDS | Protected Wire Distribution System | In English | → Electrical 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 → Engineering, technology |
| PWT | Propulsion Wind Tunnel | In English | → Vehicle engineering |
| QAM | Quadrature Amplitude Modulation | In English | → Telecommunications |
| QANTAS | Queensland And Northern Territories Airline System | In English | → Transport and postal services |
| QCM | Quartz Crystal Microbalance | In English | → Electronics |
| Qe2 | Quantock Energy & Environment | In English | → Energy economics |
| QFB | Químico Farmacobiología | In Spanish | → Biochemistry, biophysics → Pharmacology, toxicology |
| QFP | Quad Flat Pack | In English | → Electronics |
| QFT | Quantum Field Theory | In English | → Agricultural sciences |
| QİÇS | Qazanılmış İmmun Çatışmazlığı Sindromu = AIDS | Acquired Immune Deficiency Syndrome | In English = SIDA | Syndrome d'Immuno-Déficience Acquise | In French = VIGS | Verworwe Immuniteitsgebreksindroom | In Afrikaans = SIDA | Síndrome de Inmuno-Deficiencia Adquirida | In Occitan = SIDA | Sindromo di Imuno-Defekteso Aquirita | In Ido = AIDS | Akirita Imuno-Deficita Simptomaro | In Esperanto = SIDA | Sindrome d'inmunodefizienzia aquirita | In Aragonese = СПИН | Синдром на придобитата имунна недостатъчност | In Bulgarian = SIDA | Síndrome d'Immunodeficiència Adquirida | In Catalan = HIES | Hartutako Immuno Eskasiaren Sindromea | In Basque = SIDA | Síndrome de Inmunodeficiencia Adquirida | In Spanish = SEIF | Siondróm Easpa Imdhíonachta Faighte | In Irish = AIDS | Annlochd Inneamh Dìon-Slàinte | GD = ՁԻԱՀ | Ձեռքբերովի Իմունային Անբավարվածության Համախտանիշ | In Armenian = SCDI | Syndromis Comparatis Defectu Immunitatis | In Latin = 에이즈 | 후천성 면역 결핍 증후군 | In Korean = შიდსი | შეძენილი იმუნური დეფიციტის სინდრომი | In Georgian = СИДА | Синдромот на стекнат имунолошки дефицит | In Macedonian = СИДА | синдром стеченог имунолошког дефицита | In Serbian = AIDS | Akvirírani imúnski deficítni sindróm | In Slovenian = СПИД | Синдром приобретённого иммунного дефицита | In Russian = SIDA | Sindromul Imunodeficienţei Autodobândite | In Romanian = UHCW | Unquy hark'aypa chaskisqa waqlliynin | In Quechua = SIDA | Síndrome da imunodeficiência adquirida | In Portuguese = AIDS | Hội chứng Suy giảm Miễn dịch Mắc phải | In Vietnamese = СНІД | Cиндром набутого імунодефіциту | In Ukrainian = AIDS | Alınğan İmmun Defisit Síndromı | In Tatar = UKIMWI | Upungufu wa Kinga Mwilini | In Swahili |
In Azerbaijani | → Immunology and allergy → Infectious diseases |
| 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 | → Engineering, technology |
| QTP | Qualification Test Plan | In English | → Engineering, technology |
| QTP | Qualification Test Procedure | In English | → Engineering, technology |
| QTR | Qualification Test Report | In English | → Engineering, technology |
| QTV | Qualification Test Vehicle | In English | → Spaceflight engineering, astronautics |
| QUAS | Quaternisation of Starch Producers Association | In English | → Associations → Chemical technology |
| QVT | Qualified Verification Testing | In English | → Engineering, technology |
| R&CC | Recorder and Communication Control | In English | → Telecommunications |
| 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 → Engineering, technology |
| R&D | Recherche et développement = F&E, I+D, R&S, P&D, O&O, FoU (look above) |
In French | → Research policy → Engineering, technology |
| R&DO | Research and Development Operations | In English | → Research policy → Engineering, technology |
| R&E | Research and Engineering | In English | → Research policy → Engineering, technology |
| R&S | Ricerca e Sviluppo = R&D, F&E, I+D, P&D, O&O, FoU (look above) |
In Italian | → Research policy → Engineering, technology |
| R&T | Research and Technology | In English | → Research policy → Engineering, technology |
| R2I | Réseau Industriel d'Innovation | In French | → Research policy → Industry, industrial policy → Engineering, technology |
| R2ITH | Réseau Industriel d'Innovation du Textile et de l'Habillement | In French | → Textile industry |
| 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 |
| RABF | Radio Astronomy Bandstop Filter | In English | → Astronomy → Telecommunications |
| RACC | Radio Advertising Clearance Centre | In English | → Telecommunications → 659 |
| 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 | → Telecommunications |
| 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 |
| RAG | Rohöl-Aufsuchungs Aktiengesellschaft | In German | → Chemical technology |
| RAGIE | Red Avanzada Guatemalteca para la Investigación y Educación | In Spanish | → Computer science → Education → Mathematics and natural sciences → Telecommunications |
| RAI | Radio Audizioni Italiane | In Italian | → Telecommunications |
| RAI | Radar Altimeter Indicator | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RAI | Radiotelevisione Italiana | In Italian | → Telecommunications |
| 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 |
| RALPH | Reduction and Acquisition Of Lunar Pulse Heights | In English | → Astronomy → Spaceflight engineering, astronautics |
| RALT | Radar Altimeter | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| RAMC | Régime Canadien d'Accès aux Médicaments = CAMR | Canada's Access to Medicines Regime | In English |
In French | → Pharmacology, toxicology |
| RANN | Research Applied to National Needs | In English | → Research policy → Engineering, technology |
| RAPCON | Radar Approach and Control | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| 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 |
| 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 |
| RATCC | Radar Air Traffic Control Center | In English | → Aeronautics, aircraft |
| RATO | Rocket-Assisted Takeoff | In English | → Spaceflight engineering, astronautics |
| RATP | Régie Autonome des Transports Parisiens | In French | → Transport and postal services |
| RAU | Red Académica Uruguaya | In Spanish | → Computer science → Higher education, universities → Telecommunications |
| 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 |
| RC | Reinforced Concrete | In English | → Building |
| RC | Resistance-Capacitance | In English | → Electrical engineering |
| RCA | Radio Corporation of America | In English | → Telecommunications |
| 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 |
| RCCP | Recorder and Communications Control Panel | In English | → Telecommunications |
| RCD | Réacteur Complétement Déchargé | In French | → Nuclear technology |
| RCF | Radios Chrétiennes en France | In French | → Organizations and associations → Telecommunications → Christianity |
| RCN | Rockwell Communication Network | In English | → Telecommunications |
| RCO | Rencontres Chimiques de l’Ouest | In French | → Specialized or (poly)technical colleges → Chemistry → Chemical technology |
| RCO | Radio Comptoir de l'Ouest (www.rco.fr) | In French | → Telecommunications → Electronics |
| RCP | Réanimation cardiopulmonaire | In French | → Traumatology |
| RCP | Résumé des Caractéristiques du Produit = SPC | Summary of Product Characteristics | In English |
In French | → Pharmacology, toxicology |
| RCS | Reentry Control System | In English | → Spaceflight engineering, astronautics |
| RCSO-TIC | Réseau de Compétences de Suisse Occidentale en Technologie de l'Information et de la Communication | In French | → Computer science → Telecommunications |
| RD | Rétinopathie Diabétique | In French | → Pathology → Ophtalmology |
| RDA | Recommended Dietary Allowances = ADH | Aanbevolen Dagelijkse Hoeveelheid | In Dutch = ADI | Acceptabel Daglig Indtagelse | In Danish |
In English | → Personal health and hygiene |
| RDF | Radio Direction Finding | In English | → Telecommunications |
| RDF | Radio Direction Finder | In English | → Telecommunications |
| RDO | Radio Dom Ostankino | In Russian | → Telecommunications |
| RDR | Règlement de Développement Rural | In French | → Agricultural sciences → Regional planning |
| RDS | Rocketdyne Digital Simulator | In English | → Spaceflight engineering, astronautics |
| RDS-TMC | Radio Data System - Traffic Message Channel | In English | → Transport and postal services |
| RDT | Réseau de Développement Technologique | In French | → Engineering, technology |
| RDTC | Réseau de Développement Technologique Corse | In French | → Engineering, technology |
| RE | Responsible Engineer | In English | → Engineering, technology |
| RE | Reproductive Endocrinologist | In English | → Reproductive biology |
| REA | Rocket Engine Assembly | In English | → Spaceflight engineering, 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 | → 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 |
| 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 |
| 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 |
| REM | Roentgen Equivalent Man | In English | → Radioactivity → Medicine |
| 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 |
| 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 |
| REP | Réacteur à Eau Pressurisée = PWR, DWR (look above) |
In French | → Nuclear technology |
| REPOM | Réseau national de surveillance des ports maritimes | In French | → Transport and postal services |
| RESC | Réacteur à Eau SuperCritique | In French | → Nuclear technology |
| 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 |