| MTCU | Magnetic Tape Control Unit | In English | |
| MTDM | Mechanics of Time-Dependent Materials | In English | → Serial publications, periodicals → Mechanical engineering |
| MTE | Multisystem Test Equipment | In English | |
| MTE | Maintenance Test Equipment | In English | → Maintenance and logistics |
| MTEC | Maintenance Test Equipment Catalog | In English | → Maintenance and logistics |
| MTEE | Maintenance Test Equipment, Electrical | In English | → Maintenance and logistics → Electrical engineering |
| MTEF | Maintenance Test Equipment, Fluid | In English | → Maintenance and logistics |
| MTEM | Maintenance Test Equipment, Mechanical | In English | → Maintenance and logistics → Mechanical engineering |
| MTEM | Maintenance Test Equipment Module | In English | → Maintenance and logistics |
| MTEO | Maintenance Test Equipment, Optical | In English | → Maintenance and logistics |
| MTFF | Man-Tended Free Flyer | In English | |
| MTFF | Man-Tended Free-Flyer | In English | |
| MTFO | Modular Training Field Option | In English | |
| MTG | Master Timing Generator | In English | |
| MTG | Music Technology Group | In English | → Computer-based techniques → Music |
| MTGP | Monitor Table Generator Program | In English | |
| MTGW | Maximum Total Gross Weight | In English | |
| MTI | Morton Thiokol, Incorporated | In English | |
| MTI | Moving-Target Indicator | In English | |
| MTJ | Mobile Tools for Java | In English | → Software |
| MTK | Mechanical Timekeeping | In English | → Mechanical engineering |
| MTK | Mechanized Timekeeping | In English | → Mechanical engineering |
| MTL | Main Transfer Line | In English | |
| mTLD | mobile Top Level Domain | In English | → Networks, communication → Telecommunications |
| MTLP | Monitor Table Listing Program | In English | |
| MTM | Mechanical Test Model | In English | → Mechanical engineering |
| MTM | Method of Task Measurement | In English | |
| MTM | Methods Time Measurement | In English | |
| MTM | Multiterminal Monitor | In English | → Human-computer interaction |
| MTMO | Mated Test Management Office | In English | |
| MTO | Mission Task Objective | In English | |
| MTO | Maximum Time-Out | In English | |
| MTO | Master Timing Oscillator | In English | |
| MTO | Magnetic Tape Operator | In English | |
| MTO | Modification Task Outline | In English | |
| MTO | Mississippi Test Operations | In English | |
| MTOGW | Maximum Takeoff Gross Weight | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| mTOR | Mammalian Target Of Rapamycin | In English | → Biochemistry, biophysics → Mammals |
| MTOW | Maximum Takeoff Weight | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MTP | Manufacturing Technical Procedure | In English | → Engineering, technology |
| MTP | Mission Test Plan | In English | |
| MTP | Master Test Plan | In English | |
| MTPE | Mission To Planet Earth | In English | → Planets and satellites → Spaceflight engineering, astronautics |
| MTR | Magnetic Tape Recorder | In English | |
| MTRD | Master Test Requirement Document | In English | |
| MTS | Motor-Operated Transfer Switch | In English | |
| MTS | Mobile Tracking Station | In English | |
| MTS | Metric Time System | In English | |
| MTS | Magnetic Tape Station | In English | |
| MTS | Magnetic Tape System | In English | |
| MTS | Main Thruster Subsystem | In English | → Vehicle engineering |
| MTS | Master Timing System | In English | |
| MTS | Methods for Testing & Specification | In English | |
| MtSOM | Mount Stromlo Observatory Mimeographs | In English | → Serial publications, periodicals → Astronomy |
| MtSRe | Mount Stromlo Observatory Reprints | In English | → Serial publications, periodicals → Astronomy |
| MTT | Maximum Touch Temperature | In English | |
| MTTA | Mean Time To Accomplish | In English | |
| MTTE | Mean Time To Exchange | In English | |
| MTTF | Mean Time To Failure | In English | |
| MTTFF | Mean Time To First Failure | In English | |
| MTTR | Mean Time To Repair | In English | |
| MTTRF | Mean Time To Restore Function | In English | |
| MTU | Mobile Training Unit | In English | |
| MTU | Magnetic Tape Unit | In English | |
| MTU | Master Timing Unit | In English | |
| MTV | Mass Transfer Vehicle | In English | → Vehicle engineering |
| MTVC | Manual Thrust Vector Control | In English | → Vehicle engineering |
| MTW | Maximum Taxi Weight | In English | → Vehicle engineering |
| MtWAR | Mount Wilson and Palomar Observatory Annual Report | In English | → Serial publications, periodicals → Astronomy |
| MtWRe | Mount Wilson and Palomar Observatory Reprints | In English | → Serial publications, periodicals → Astronomy |
| MU | Master Unit | In English | |
| MU | Mobile Unit | In English | |
| MU | Multiple Unit | In English | |
| MUA | Mutual Usage Agreement | In English | |
| MUA | Maximum Usable Altitude | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MUA | Materials Usage Agreement | In English | |
| MUAHAG | Military Usage and Harmonization Advisory Group | In English | → Military affairs |
| MUCMENAS | Macquarie University: Centre for Middle East and North African Studies | In English | → Language, linguistics, literature → Geography, biography, history |
| MUF | Maximum Usable Frequency | In English | |
| MUL | Mission-Unique List | In English | |
| MULSS | Multiple Light Scattering System | In English | → Optics |
| MUMPS | Massachusetts General Hospital Utility Multi-Programming System | In English | → Programming languages → Medicine |
| MUNEE | Municipal Networks for Energy Efficiency | In English | → Public administration, government → Energy economics |
| MUPPS | Mission-Unique Planning and Processing Schedule | In English | |
| MUR | Manpower Utilization Report | In English | |
| MURI | Multi-disciplinary Research Initiative | In English | → Research policy → Mathematics and natural sciences |
| MUS | Mission-Unique Software | In English | → Software |
| MUSE | Medicated Urethral System for Erection | In English | → 3926 → Urology |
| MUSIC | Multiple Signal Classification | In English | → Networks, communication → Telecommunications |
| MUSS | Module Utility Support Structure | In English | |
| MUST | Modelling the Use and Safety of Transport = MUST | Modélisation de l'Usage et de la Sécurité des Transports | In French |
In English | → Vehicle engineering → Transport and postal services |
| MV | Manual Valve | In English | |
| MV | Manufacturing Verification | In English | → Engineering, technology |
| MVAS | Multipurpose Ventricular Actuating System | In English | |
| MVC | Master Volume Control | In English | |
| MVC | Manual Volume Control | In English | |
| MVD | Map and Visual Display | In English | → Human-computer interaction |
| MVF | Manned Vertical Flight | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| MVGVT | Mated Vertical Ground Vibration Test | In English | |
| MVI | Microgravity Vestibular Investigation | In English | → Astronomy → Spaceflight engineering, astronautics |
| MVL | Multilamellar Vesicle | In English | → Biotechnology → Pharmacology, toxicology |
| MVM | Mariner Venus/Mercury | In English | → Astronomy → Spaceflight engineering, astronautics |
| MVMA | Maryland Veterinary Medical Association (www.mdvma.org) | In English | → Associations → Veterinary medicine |
| MVO | Montserrat Volcano Observatory (www.mvo.ms) | In English | → Research institutes → 55121 |
| MVP | Master Verification Plan | In English | |
| MVR | Measurement Velocity Radial | In English | |
| MVS | Middle-Value Select | In English | |
| MVS | Multiple Virtual Storage | In English | → Memories |
| MVWT | Mated Vehicle Wind Tunnel | In English | → Vehicle engineering |
| MW | Microwave | In English | |
| MW | (The) Muslim World | In English | → Islam → Area studies |
| MWA | Mental Workload Analyzer | In English | |
| MWB | Master Workbook | In English | |
| MWC | Mobile World Congress | In English | → Congresses → Telecommunications |
| MWD | Material Withdrawal Document | In English | → Maintenance and logistics |
| MWG | Maintainability Working Group | In English | → Maintenance and logistics |
| MWIR | Medium-Wavelength Infrared | In English | |
| MWOAR | Mount Wilson Observatory Annual Report | In English | → Serial publications, periodicals → Astronomy |
| MWOR | Maintenance Work Order Request | In English | → Maintenance and logistics |
| MWP | Maximum Working Pressure | In English | |
| MWPR | Monthly Work Package Report | In English | → Management |
| MWR | Mean Width Ratio | In English | |
| MWRv | Monthly Weather Review | In English | → Serial publications, periodicals → Meteorology, climatology |
| MWS | Missile Weapon System | In English | → Military engineering |
| MWV | Maximum Working Voltage | In English | → Electrical engineering |
| MXML | Macromedia Flex Markup Language | In English | → Programming languages |
| MYTA | Maintainability Task Analysis | In English | → Maintenance and logistics |
| MYVAL | Maintainability Evaluation | In English | → Maintenance and logistics |
| MZFW | Maximum Zero Fuel Weight | In English | |
| N | Nitrogen = N | Azote | In French = N | Stikstof | In Afrikaans = N | نيتروجين | In Arabic = N | Nitróxenu | In Asturian = N | Azot | In Azerbaijani = N | Азот | In Belarusian = N | Азот | In Bulgarian = N | নাইট্রোজেন | In Bengali = N | Dušik | In Bosnian = N | Nitrogen | In Catalan = N | Azotu | In Corsican = N | Dusík | In Czech = N | Азот | In Chuvash = N | Nitrogen | In Welsh = N | Kvælstof | In Danish = N | Stickstoff | In German = N | Άζωτο | In Greek = N | Azoto | In Esperanto = N | Nitrógeno | In Spanish = N | Lämmastik | In Estonian = N | Nitrogeno | In Basque = N | نیتروژن | In Persian = N | Typpi | In Finnish = N | Azôt | In Friulian = N | Nítrigin | In Irish = N | Nitróxeno | In Galician = N | નાઇટ્રોજન | In Gujarati = N | Neetragien | In Manx = N | חנקן | In Hebrew = N | नाइट्रोजन | In Hindi = N | Dušik | In Croatian = N | Azòt | In Haitian Creole = N | Nitrogén | In Hungarian = N | Ազոտ | In Armenian = N | Nitrogeno | In Interlingua = N | Nitrogen | In Indonesian = N | Nitro | In Ido = N | Nitur | In Icelandic = N | Azoto | In Italian = N | 窒素 | In Japanese = N | trano | In Lojban = N | აზოტი | In Georgian = N | 질소 | In Korean = N | Stickstoff | In Kölsch = N | Nîtrojen | In Kurdish = N | Nitrogenium | In Latin = N | Stéckstoff | In Letzeburgesh = N | Stikstof | In Limburgish = N | Azoti | In Lingala = N | Azotas | In Lithuanian = N | Slāpeklis | In Latvian = N | Hauota | In Māori = N | Азот | In Macedonian = N | നൈട്രജന് | In Malayalam = N | Азот | In Mongolian = N | नायट्रोजन | In Marathi = N | Ehēcatehuiltic | En Nahuatl = N | Stickstoff | In Low German = N | Stikstof | In Dutch = N | Nitrogen | In Nynorsk = N | Nitrogen | In Norwegian = N | Nitrogene | NOV = N | Azòt | In Occitan = N | Nitrogen | In Kapampangan = N | Azot | In Polish = N | Nitrogénio | In Portuguese = N | Qullpachaq | In Quechua = N | Azot | In Romanian = N | Азот | In Russian = N | Azzotu | In Sicilian = N | Dušik | In Serbo-Croatian = N | Dusík | In Slovak = N | Dušik | In Slovenian = N | Azoti | In Albanian = N | Азот | In Serbian = N | Kväve | In Swedish = N | Nitrojeni | In Swahili = N | நைட்ரஜன் | In Tamil = N | నత్రజని | In Telugu = N | Азот | In Tajik = N | ไนโตรเจน | In Thai = N | Azot | In Turkish = N | Азот | In Ukrainian = N | Azot | In Uzbek = N | Nitơ | In Vietnamese = N | 氮 | In Chinese |
In English | → Chemistry |
| N | Asparagine = N | Asparagina | In Catalan = N | Asparagin | In German = N | Asparagina | In Spanish = N | Asparagino | In Esperanto = N | Asparagine | In French = N | 아스파라긴 | In Japanese = N | Asparagin | In Indonesian = N | Asparagina | In Italian = N | אספרגין | In Hebrew = N | Asparagīns | In Latvian = N | Asparagin | In Letzeburgesh = N | Asparaginas | In Lithuanian = N | Asparagine | In Dutch = N | アスパラギン | In Japanese = N | Asparagina | In Polish = N | Asparagina | In Portuguese = N | Аспарагин | In Russian = N | Asparagín | In Slovak = N | Аспарагин | In Serbian = N | Asparagiini | In Finnish = N | Asparagin | In Swedish = N | Asparagin | In Turkish = N | Аспарагін | In Ukrainian = N | 天冬酰胺 | In Chinese |
In English | → Biochemistry, biophysics |
| N2H2 | Hydrazine | In English | → Chemistry |
| NA | Numerical Aperture | In English | |
| Na | Sodium = Na | Sodium | In French = Na | Natrium | In Afrikaans = Na | صوديوم | In Arabic = Na | Sodiu | In Asturian = Na | Натрый | In Belarusian = Na | Натрий | In Bulgarian = Na | সোডিয়াম | In Bengali = Na | Natrijum | In Bosnian = Na | Sodi | In Catalan = Na | Sodiu | In Corsican = Na | Sodík | In Czech = Na | Sodiwm | In Welsh = Na | Natrium | In Danish = Na | Natrium | In German = Na | ސޯޑިއަމް | In Dhivehi = Na | Νάτριο | In Greek = Na | Natrio | In Esperanto = Na | Sodio | In Spanish = Na | Naatrium | In Estonian = Na | Sodio | In Basque = Na | سدیم | In Persian = Na | Natrium | In Finnish = Na | Sodi | In Friulian = Na | Sóidiam | In Irish = Na | Sodio | In Galician = Na | Sodjum | In Manx = Na | נתרן | In Hebrew = Na | सोडियम | In Hindi = Na | Natrij | In Croatian = Na | Sodyòm | In Haitian Creole = Na | Nátrium | In Hungarian = Na | Նատրիում | In Armenian = Na | Natrium | In Indonesian = Na | Natro | In Ido = Na | Natrín | In Icelandic = Na | Sodio | In Italian = Na | ナトリウム | In Japanese = Na | sodna | In Lojban = Na | Natrium | JV = Na | ნატრიუმი | In Georgian = Na | ಸೋಡಿಯಮ್ | In Kannada = Na | 나트륨 | In Korean = Na | Natrîyûm | In Kurdish = Na | Natrium | In Latin = Na | Natrium | In Letzeburgesh = Na | Sodu | In Lingala = Na | Natris | In Lithuanian = Na | Nātrijs | In Latvian = Na | Konutai | In Māori = Na | Натриум | In Macedonian = Na | സോഡിയം | In Malayalam = Na | सोडियम | In Marathi = Na | Natrium | In Low German = Na | Natrium | In Dutch = Na | Natrium | In Nynorsk = Na | Natrium | In Norwegian = Na | Natrium | NOV = Na | Sôdgium | In Norman = Na | Sòdi | In Occitan = Na | Sód | In Polish = Na | Sódio | In Portuguese = Na | Natriyu | In Quechua = Na | Sodiu | In Romanian = Na | Натрий | In Russian = Na | Sodiu | In Sicilian = Na | Natrij | In Serbo-Croatian = Na | Sodík | In Slovak = Na | Natrij | In Slovenian = Na | Natriumi | In Albanian = Na | Натријум | In Serbian = Na | Natrium | In Swedish = Na | Natiri | In Swahili = Na | சோடியம் | In Tamil = Na | సోడియమ్ | In Telugu = Na | Натрий | In Tajik = Na | โซเดียม | In Thai = Na | Sodyum | In Turkish = Na | Натрій | In Ukrainian = Na | Natriy | In Uzbek = Na | Natri | In Vietnamese = Na | Sodiom | In Walloon = Na | 钠 | In Chinese |
In English | → Chemistry |
| NA | Network Aspects | In English | → Networks, communication |
| NAA | North American Aircraft | In English | → Spaceflight engineering, astronautics |
| NAAAID | National Association of Americans of Asian Indian Descent | In English | → Associations → Genealogy |
| NAAAP | National Association of Asian American Professionals | In English | → Associations → Labour, labour economics |
| NAAB | National Association of Animal Breeders (www.naab-css.org) | In English | → Associations → Agricultural sciences |
| NAACLT | North American Association for Celtic Language Teachers (www.naaclt.org) | In English | → Associations → Education → Language, linguistics, literature |
| NAACP | National Association for the Advancement of Colored People | In English | → Associations → Labour, labour economics |
| NaAIJ | Nanjing Aeronautical Institute Journal | In English | → Serial publications, periodicals → Aeronautics, aircraft |
| NAAL | North American Aerodynamic Laboratory | In English | → Research institutes → Aerodynamics |
| NAATA | National Asian American Telecommunications Association | In English | → Associations → Telecommunications |
| NABA | North American Broadcasters Association (www.nabanet.com) | In English | → Associations → Telecommunications |
| NABR | National Association for Biomedical Research (www.nabr.org) | In English | → Associations → Biological sciences → Medicine |
| NABT | National Association of Biology Teachers (www.nabt.org) | In English | → Associations → Education → Biological sciences |
| NAC | Naval Avionics Center | In English | → Aeronautics, aircraft |
| NACA | National Advisory Committee for Aeronautics | In English | → Aeronautics, aircraft |
| NACBS | North American Conference on British Studies | In English | → Organizations and associations → Area studies |
| NACCP | National Association of Child Care Professionals | In English | → Associations → Pediatry |
| NACEC | North American Commission for Environmental Cooperation (www.cec.org) = CCAAN | Comisión para la Cooperación Ambiental de América del Norte | In Spanish = CNACE | Commission Nord-Américaine de Coopération Environnementale | In French = CNACA | Comissão Norte-americana de Cooperação Ambiental | In Portuguese |
In English | → International relations → Nature |
| NACS | Nordic Association for China Studies | In English | → Associations → Language, linguistics, literature → Geography, biography, history |
| NAD | Nicotinamide Adenine Dinucleotide | In English | → Genetics → Biochemistry, biophysics |
| NAD | Network Adapter Device | In English | → Hardware → Networks, communication |
| NADS | Norwegian Association for Defence Suppliers | In English | → Associations → Military engineering |
| NAEC | Northeast Asia Economic Conference | In English | → Economics |
| NAEC | Naval Air Engineering Center | In English | → Aerodynamics → Aeronautics, aircraft |
| NAEP | National Assessment of Educational Progress | In English | → Education |
| NAERIC | North American Equine Ranching Information Council | In English | → Organizations and associations → Agricultural sciences |
| NAES | National Association for Ethnic Studies | In English | → Associations → Ethnology |
| NAEYC | National Association for the Education of Young Children | In English | → Associations → Education |
| NAFFAA | National Federation of Filipino American Associations | In English | → Organizations and associations |
| NAFO | Northwest Atlantic Fisheries Organisation (www.nafo.int) | In English | → Organizations and associations → Fishing, hunting |
| NAFTA | North American Free Trade Agreement | In English | → International economic cooperation |
| NaGe | National Geographic | In English | → Serial publications, periodicals → Area studies → Geography |
| NAGINELS | Non Aggressive Glass Internal Engraving Laser System | In English | → Engineering, technology |
| NAGMC | National Association of Girls and Mixed Clubs | In English | → Associations |
| NAHRA | North American Riding for the Handicapped Association | In English | → Associations → Sport, physical exercises |
| NAIA | National Animal Interest Alliance (www.naiaonline.org) | In English | → Organizations and associations → Nature and society |
| NAJAKS | Nordic Association for Japanese and Korean Studies | In English | → Associations → Language, linguistics, literature → Geography, biography, history |
| NAJS | Nordic Association for the Study of Contemporary Japanese Society | In English | → Associations → Language, linguistics, literature → Geography, biography, history |
| NAL | National Agricultural Library (www.nal.usda.gov) | In English | → Libraries → Agricultural sciences |
| NAM | National Association of Manufacturers | In English | → Associations → Engineering, technology |
| NAM | Nuclear Assessment Methodology | In English | → Nuclear technology |
| NAMS | North American Micropaleontology Section | In English | → Organizations and associations → Palaeontology |
| NAOJ | National Astronomical Observatory of Japan | In English | → Observatories |
| NAOMI | North American OpenMath Initiative | In English | → Computer science → Mathematics |
| NAP | Navigation Analysis Program | In English | → Vehicle engineering → Transport and postal services |
| NAP | National Action Plan | In English | |
| NAP | National Allocation Plan | In English | |
| NAP | National Action Programme | In English | |
| NAPABA | National Asian Pacific American Bar Association | In English | → Associations → Law, jurisprudence |
| NAPCC | National Animal Poison Control Center | In English | → Organizations and associations → Pharmacology, toxicology → Veterinary medicine |
| NAPCTC | North American Policy Council for OSI (Open Systems Interconnection) Testing and Certification | In English | → Computer science |
| NAPH | National Association of Professors of Hebrew (http://polyglot.lss.wisc.edu/naph/) | In English | → Associations → Education → Language, linguistics, literature |
| NAPPS | National Association of Professional Pet Sitters (www.petsitters.org) | In English | → Associations |
| NAPQI | N-Acetyl-p-Benzoquinone Imine | In English | |
| NAR | National Association of Realtors | In English | → Associations → Accommodation |
| NAR | Numerical Analysis Research | In English | → Computer-based techniques |
| NAR | Nucleic Acids Research | In English | → Serial publications, periodicals → Biochemistry, biophysics |
| NARME | Natural Resources Management and Ecological Engineering | In English | → Environment, environmental sciences → Ecology |
| NARR | North American Regional Reanalysis | In English | → Meteorology, climatology |
| NARS | National Archives and Record Services | In English | → Libraries |
| NAS | National Aircraft Standard | In English | → Standardization → Aeronautics, aircraft |
| NAS | National Airspace System | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| NAS | Naval Air Station | In English | → Public administration, government → Aeronautics, aircraft |
| NAS | Nonavionics Simulator | In English | → Computer simulation → Aeronautics, aircraft |
| NAS | Numerical Aerodynamic Simulation | In English | → Computer simulation → Aerodynamics |
| NAS | National Academy of Sciences | In English | → 06112 → Mathematics and natural sciences |
|