| MAE | Mesures Agri-Environnementales | In French | → Nature → Agricultural sciences |
| MAEA | Międzynarodowa Agencja Energii Atomowej (www.iaea.org) = IAAE | Internacia Agentejo pri Atom-Energio | In Esperanto = IAEA | International Atomic Energy Agency | In English = AIEA | Agence Internationale de l'Énergie Atomique | In French = AIEA | Agenţia Internaţională pentru Energie Atomică | In Romanian = МААЕ | Международна агенция за атомна енергия | In Bulgarian = AIEA | Agència Internacional de l'Energia Atòmica | In Catalan = MAAE | Mezinárodní agentura pro atomovou energii | In Czech = IAEA | Det Internationale Atomenergiagentur | In Danish = IAEO | Internationale Atomenergieorganisation | In German = OIEA | Organismo Internacional de Energía Atómica | In Spanish = סבא"א | הסוכנות הבינלאומית לאנרגיה אטומית | In Hebrew = IAEA | International Atomenergie Agence | In Letzeburgesh = AIEA | Agenzia Internazionale per l'Energia Atomica | In Italian = IAEA | अंतर्राष्ट्रीय परमाणु ऊर्जा अधिकरण | In Hindi = MAAE | Меѓународна агенција за атомска енергија | In Macedonian = МАГАТЭ | Международное агентство по атомной энергии | In Russian = AIEA | Agência Internacional de Energia Atómica | In Portuguese = МАГАТЕ | Міжнародне агентство з атомної енергії | In Ukrainian = UAEA | Uluslararası Atom Enerji Ajansı | In Turkish = IAEA | สำนักงานพลังงานปรมาณูระหว่างประเทศ | In Thai = EANA | Energia Atomikoaren Nazioarteko Agentzia | In Basque |
In Polish | → International relations → Energy economics → Nuclear technology |
| MAEH | Mouvement pour l'Amélioration de l'Environnement Hospitalier | In French | → Organizations and associations → Medicine |
| MAEP | Minimum Autoland Entry Point | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MAES | Malopolska Agencja Energii i Srodowiska | In Polish | → Energy economics |
| MAF | Mixed Amine Fuel | In English | → Vehicle engineering |
| MAFF | Ministry of Agriculture, Food and Fisheries | In English | → Central administration → Agricultural sciences → Fishing, hunting → Food technology |
| MAGALI | Moyens Aixois de Gestion des Automobiles par Localisation Informatique | In French | → Automobile manufacturing → Transport and postal services |
| MAGSAT | Magnetometer Satellite | In English | → Spaceflight engineering, astronautics → Physics → Earth sciences |
| MAI | Mécanique et Automatismes Industriels | In French | → Mechanical engineering |
| MAIF | Maryland Automobile Insurance Fund | In English | → Insurance → Automobile manufacturing |
| Mockup And Integration Laboratory | In English | → Research institutes → Mechanical engineering |
|
| MAL | Model Assembly List | In English | → Engineering, technology |
| MAL | Mobile Airlock | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MALC | Metal Articles Liaison Committee | In English | → Organizations and associations → Metallurgy |
| MALT | Model Assembly List Transmittal | In English | → Engineering, technology |
| MAN | Microwave Aerospace Navigation | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MAN | Médecine d'Afrique Noire | In French | → Serial publications, periodicals → Medicine |
| MANTECH | Manufacturing Technology | In English | → Engineering, technology |
| MAP | Multiple Antigenic Peptide | In English | → Biochemistry, biophysics → Immunology and allergy |
| MAP | Manufacturing Automation Protocol | In English | → Engineering, technology |
| MAPCM | Molecular Alloys Phase Change Material | In English | → Chemical technology |
| MAPDR | Ministerul Agriculturii, Pădurilor şi Dezvoltării Rurale | In Romanian | → Central administration → Agricultural sciences |
| MAPEC | Multimedia Applications in Education Conference | In English | → Education → Telecommunications |
| MAPS | Measurement of Air Pollution from Satellites | In English | → Nature → Meteorology, climatology → Spaceflight engineering, astronautics |
| MARAD | Maritime Administration (www.marad.dot.gov) | In English | → Central administration → 6295 → Transport and postal services |
| MaRBu | Materials Research Bulletin | In English | → Serial publications, periodicals → 620 |
| MARC | Multiple Artificial Retina Chipset | In English | → Medicine → Electronics |
| MARN | Mission d'Appui à la gestion du Risque Nucléaire | In French | → Nuclear technology |
| MARNIS | Maritime Navigation and Information Services | In English | → Marine research, oceanography → Transport and postal services |
| MARS | Manned Astronautical Research Station | In English | → Spaceflight engineering, astronautics |
| MARS | Modular Airborne Recorder System | In English | → Aeronautics, aircraft |
| MARSOUIN | Môle Armoricain de Recherche sur la SOciété de l'Information et les Usages d 'Internet | In French | → Networks, communication → Telecommunications |
| MAS | Medium-Altitude Sensor | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MAS | Morbus Alzheimer Syndrom | In German | → Neurology |
| MASCOTTE | Méthodes Algorithmiques, Simulation, Combinatoire et OpTimisation pour les TElécommunications | In French | → Computer science → Telecommunications |
| MASDC | Military Aircraft Storage and Disposition Center | In English | → Military engineering → Spaceflight engineering, astronautics |
| MASSPO | Manned Spaceflight Support Project Office | In English | → Spaceflight engineering, astronautics |
| MAT | Microangiopathie thrombotique | In French | → Blood and circulatory system → Pathology |
| MatEv | Materials Evaluation | In English | → Serial publications, periodicals → 620 |
| MatL | Materials Letters | In English | → Serial publications, periodicals → 620 |
| MatST | Materials Science Technology | In English | → Serial publications, periodicals → 620 |
| MatTe | Matériaux et Techniques | In French | → Serial publications, periodicals → 620 |
| MatTr | Materials Transactions | In English | → Serial publications, periodicals → 620 |
| MAV | Malformation artérioveineuse | In French | → Pathology |
| MBAC | Marshall Booster Assembly Contractor | In English | → Spaceflight engineering, astronautics |
| MBC | Maximum Breathing Capacity | In English | → Anatomy |
| MBE | Molecular Beam Epitaxy = EJM | Épitaxie par Jets Moléculaires | In French |
In English | |
| MBFP | Manufacturing Build and Flow Plan | In English | → Engineering, technology |
| MBK | Medications and Bandage Kit | In English | → Medicine |
| MBS | Malagasy Broadcasting System | In English | → Telecommunications |
| MBV | Mauritius Buch Verlag | In German | → Graphic industries, printing, publishing |
| MC | Machine Check | In English | → Engineering, technology |
| MC | Military Characteristic | In English | → Military engineering |
| MCA | Maximum Crossing Altitude | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MCAE | Mechanical Computer Aided Engineering | In English | → Computer-based techniques → Mechanical engineering |
| MCAT | Missile Carrier Air Transport | In English | → Military engineering → Aeronautics, aircraft |
| MCBO | Molecular Cell Biology and Oncology Graduate Program | In English | → Education → Cytology → Oncology |
| MCC | Main Combustion Chamber | In English | → Vehicle engineering |
| MCF | Military Computer Family | In English | → Hardware → Military engineering |
| MCH | Mean Corpuscular Haemoglobin = HCM | Hémoglobine Corpusculaire Moyenne | In French |
In English | → Blood and circulatory system |
| MCH | Medisch Centrum Haaglanden | In Dutch | → Medicine |
| MCHC | Mean Cell Hemoglobin Concentration | In English | → Blood and circulatory system |
| MCHC | Mean Corpuscular Hemoglobin Concentration = CCMH | Concentration Corpusculaire Moyenne en Hémoglobine | In French |
In English | → Blood and circulatory system |
| MCHC | Metropolitan Chicago Healthcare Council | In English | → Organizations and associations → Medicine |
| MCHC | Minnesota Chinese Health Center | In English | → Medicine |
| MCHC | Family Health Bureau | In English | → Medicine |
| MCHC | Maternal and Child Health Coalition | In English | → Organizations and associations → Gynaecology → Pediatry |
| MCI | Mild Cognitive Impairment | In English | → Neurology |
| MCJ | Maladie de Creutzfeldt-Jakob | In French | → Neurology |
| MCL | Mass Cargo Lander | In English | → Vehicle engineering |
| MCL | Materials Center Leoben | In English | → Research institutes → 62039 → 620 → 67 |
| MCLT | Maximum Cruise Level Thrust | In English | → Vehicle engineering |
| MCM | Multi Chip Module | In English | → Electronics |
| MCNV | Medisch Comité Nederland-Vietnam | In Dutch | → Organizations and associations → Medicine |
| MCP | Military Construction Program | In English | → Military engineering |
| MCP | Materials Chemistry and Physics | In English | → Serial publications, periodicals → Physics → Chemistry → 620 |
| MCP | Mission de Coopération Phytosanitaire | In French | → Agricultural sciences |
| MCP | Monocyte Chemoattractant Protein | In English | → Biochemistry, biophysics → Immunology and allergy |
| MCR | Monte-Carlo Radiodiffusion | In French | → Telecommunications |
| MCR | Molded Carrier Ring | In English | → Electronics |
| MCT | Mercury, Cadmium, Telluride | In English | → Metallurgy |
| MCT | Maximum Climb Thrust | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MCTI | Ministerul Comunicaţiilor şi Tehnologiei Informaţiei | In Romanian | → Computer science → Central administration → Telecommunications |
| MCV | Mean Corpuscular Volume = VGM | Volume Globulaire Moyen | In French |
In English | → Blood and circulatory system |
| MCVP | Materials Control and Verification Program | In English | → 620 |
| MDA | Motor Drive Amplifier | In English | → Vehicle engineering |
| MDA | Manufacturing Design Analysis | In English | → Engineering, technology |
| MDCK | Madin–Darby Canine Kidney | In English | → Biological sciences → Anatomy |
| MDCS | Material Data Collection System | In English | → Data → 620 |
| MDDS | Material Directory Data Sheet | In English | → Data → 620 |
| MDE | Modular Display Electronics | In English | → Electronics |
| MDE | Maîtrise de la Demande d’Énergie | In French | → Energy economics |
| MDE | Maîtrise de la Demande en Électricité | In French | → Energy economics → Electrical engineering |
| MDF | Manipulator Development Facility | In English | → Electrical engineering |
| MDF | Medium Density Fibreboard | In English | → Timber and woodworking industry |
| MDF | Medium Density Fiber | In English | → Timber and woodworking industry |
| MDM | Médecins du Monde | In French | → Organizations and associations → Medicine |
| MDR | Mitteldeutsche Rundfunk (www.mdr.de) | In German | → Telecommunications |
| MDR | Mitteldeutscher Rundfunk | In German | → Telecommunications |
| MDRC | Mongolian Development Research Center | In English | → Research policy → Engineering, technology |
| MDRS | Mars Desert Research Station | In English | → Astronomy → Spaceflight engineering, astronautics |
| MDS | Médicament Dérivé du Sang ou du plasma humain | In French | → Pharmacology, toxicology |
| ME | Metallurgical Engineer | In English | → Metallurgy |
| ME | Main Engine | In English | → Vehicle engineering |
| ME | Management Engineering | In English | → Management → Engineering, technology |
| ME | Manufacturing Engineering | In English | → Engineering, technology |
| ME&D | Manufacturing Engineering and Development | In English | → Engineering, technology |
| MEA | Main Electronics Assembly | In English | → Electronics |
| MEAR | Manufacturing Engineering Analysis Report | In English | → Engineering, technology |
| MEB | Main Electronics Box | In English | → Electronics |
| MEBA | Marine Engineers' Beneficial Association | In English | → Associations → 6295 |
| MEBO | Main Engine Burnout | In English | → Vehicle engineering |
| MEC | Main Engine Controller | In English | → Vehicle engineering |
| MECA | Missile Electronics Computer Assembly | In English | → Computer science → Electronics → Military engineering |
| MECA | Main Engine Controller Assembly | In English | → Vehicle engineering |
| MECCA | Master Electrical Common Connector Assembly | In English | → Electrical engineering |
| MecEn | Mechanical Engineering | In English | → Serial publications, periodicals → Mechanical engineering |
| MECF | Main Engine Computational Facilities | In English | → Computer science → Vehicle engineering |
| MECO | Main Engine Cutoff | In English | → Vehicle engineering |
| MECO | Mekong Energy Company Limited | In English | → Energy economics → Electrical engineering |
| MECSLSI | Mission Equipment Cargo Shuttle Launch Site | In English | → Spaceflight engineering, astronautics |
| MEDICS | Medical Information Computer System | In English | → Computer science → Medicine |
| MEDRC | Middle East Desalination Research Center (www.medrc.org) | In English | → Research institutes → Environmental technology, water supply, waste management → Chemical technology |
| MEDS | Mechanical Engineering Design System | In English | → Mechanical engineering |
| MEE | Ministère de l'Environnement et de l'Eau | In French | → Central administration → Nature and society → Hydrology → 627, |
| MEECN | Minimum Essential Emergency Communication Network | In English | → Networks, communication → Telecommunications |
| MEEI | Massachusetts Eye and Ear Infirmary | In English | → Surgery, orthopaedics, ophthalmology → Ophtalmology |
| MEEI | Mechanical Engineering Energy Institute | In English | → Energy economics → Mechanical engineering |
| MEEI | Magyar Elektrotechnikai Ellenőrző Intézetre | In Hungarian | → Electrical engineering |
| MEEREA | Malta Energy Efficiency & Renewable Energies Association | In English | → Organizations and associations → Energy economics |
| MEG | Magnetoencephalography | In English | → Neurology |
| MEG | MagnétoEncéphaloGraphe | In French | → Medicine |
| MEI | Mathematical Engineering Industry | In English | → Serial publications, periodicals → Mathematics → Engineering, technology |
| MEI | Main Engine Ignition | In English | → Vehicle engineering |
| MEK | Methylethyl Ketone | In English | → Chemical technology |
| MEK | Magyar Elektronikus Könyvtár | In Hungarian | → Electronics |
| MELC | Mechanical Engineering Liaison Committee | In English | → Organizations and associations → Mechanical engineering |
| MELF | Metal ELectrical Face | In English | → Electrical engineering |
| MELROSE | Mitsubishi Electric Road Traffic Simulation Environment | In English | → Computer simulation → Transport and postal services |
| MEM | Meteoroid Exposure Module | In English | → Astronomy → Spaceflight engineering, astronautics |
| MEM | Mid-Deck Electronics Module | In English | → Electronics |
| MEM | Mars Excursion Module | In English | → Spaceflight engineering, astronautics |
| MEMA | Meath Energy Management Agency | In English | → Energy economics |
| MEMMS | Modélisation des Écosystemes Marins et Monitoring par Satellites | In French | → Environment, environmental sciences → Marine research, oceanography → Spaceflight engineering, astronautics |
| MEMS | Mikro Elektro-Mekanik Sistem = MEMS | Micro-Electro-Mechanical System | In English |
In Turkish | → Mechanical engineering → Electrical engineering |
| MEMS | Micro-Electro-Mechanical System = (look above) |
In English | → Mechanical engineering → Electrical engineering |
| MENBO | Mediterranean Network of Basin Organisations | In English | → 626 → 627 |
| MEO | Mid Earth Orbit | In English | → Astronomy → Spaceflight engineering, astronautics |
| MEO | Manufacturing Engineering Order | In English | → Engineering, technology |
| MEP | Management Engineering Program | In English | → Management → Engineering, technology |
| MEP | Main Engine Propellant | In English | → Spaceflight engineering, astronautics |
| MeReC | Mechanics Research Communications | In English | → Serial publications, periodicals → Mechanical engineering |
| MERL | Mitsubishi Electric Research Labs (www.merl.com) | In English | → Electrical engineering |
| MERL | Materials Engineering Research Laboratory | In English | → Research institutes → 620 |
| MES | Main Engine Start | In English | → Vehicle engineering |
| MESELSI | Mission Extension Support Equipment Launch Site | In English | → Spaceflight engineering, astronautics |
| MESELSI | Mission Extension Shuttle Equipment Launch Site | In English | → Spaceflight engineering, astronautics |
| MeSH | Medical Subject Headings | In English | → Bibliography → Libraries → Medicine |
| MESH | Multimedia Semantic Syndication for Enhanced News Services (www.mesh-ip.eu) | In English | → Computer-based techniques → Telecommunications |
| MeSRM | Mémoires Scientifiques de la Revue de Métallurgie | In French | → Serial publications, periodicals → Metallurgy |
| MESSIAN | Methods for the efficient simulation of aircraft engine noise | In English | → Acoustics → Spaceflight engineering, astronautics |
| MESSOC | Model Evaluation of Space Station Operations Cost | In English | → Prices → Spaceflight engineering, astronautics |
| MET | Multielement Test | In English | → Engineering, technology |
| MET | Ministère (wallon) de l'Équipement et des Transports | In French | → Central administration → Civil engineering → Transport and postal services |
| METS | Multienvironment Test System | In English | → Engineering, technology |
| METVC | Main Engine Thrust Vector Control | In English | → Vehicle engineering |
| MEV | Mass Excursion Vehicle | In English | → Vehicle engineering |
| MEV | Mars Excursion Vehicle | In English | → Planets and satellites → Spaceflight engineering, astronautics |
| MEWG | Maintenance Engineering Working Group | In English | → Maintenance and logistics → Engineering, technology |
| MF | Melamine formaldehyde | In English | → Plastic industry |
| MFA | Manned Flight Awareness | In English | → Spaceflight engineering, astronautics |
| MFBP | Manufacturing Flow And Build Plan | In English | → Engineering, technology |
| MFC | Multiple-Flight Controller | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFC | Multiple-Flight Computer | In English | → Hardware → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFC | Manual Flight Control | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFCF | Mutuelle Familiale des Cheminots de France | In French | → Transport and postal services |
| MFCS | Manual Flight Control System | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFD | Metal Friction Device | In English | → Metallurgy |
| MFF | MDM Flight Forward | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFOA | Mercado de Futuros del Aceite de Oliva (www.mfao.es) | In Spanish | → Food technology |
| MFP | Mission Flight Plan | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFP | Microfluidic Probe | In English | → Physics |
| MFPA | Materialforschungs- und Prüfanstalt | In German | → Mathematics and natural sciences → 620 |
| MFPA | Minnesota Free Paper Association | In English | → Associations → Paper and board industry |
| MFPA | Manitoba Food Processors Association | In English | → Associations → Food technology |
| MFPA | Michigan Forestry and Park Association | In English | → Associations → Forestry |
| MFPE | Mission From Planet Earth | In English | → Astronomy → Spaceflight engineering, astronautics |
| MFR | Maximum Flight Rate | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFSK | Multifrequency Shift Keying | In English | → Telecommunications |
| MFSP | Macrofunction Signal Processor | In English | → Electronics → Telecommunications |
| MFT | Mean Flight Time | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFTAD | Master Flight Test Assignment Document | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MFTIO | Minimum Flyout Time For Orbital Interception | In English | → Spaceflight engineering, astronautics |
| MFV | Main Fuel Valve | In English | → Vehicle engineering |
| MGC | Mutuelle Générale des Cheminots | In French | → Transport and postal services |
| MGH | Massachusetts General Hospital | In English | → Medicine |
| MGK | McLaughlin Gormley King Company (www.mgk.com) | In English | → Agricultural sciences |
| MGSE | Mechanical Ground Support Equipment | In English | → Mechanical engineering |
| MGT | Major Ground Test | In English | → Engineering, technology |