| NPN | NASA Part Number | In English | → Spaceflight engineering, astronautics |
| NPNDS | Neutron Physics and Nuclear Data in Science and Technology | In English | → Serial publications, periodicals → Nuclear, atomic, and molecular physics |
| NPPC | National Pork Producers Council (www.nppc.org) | In English | → Organizations and associations → Agricultural sciences |
| NPPSB | Nonequilibrium Problems in the Physical Sciences and Biology | In English | → Serial publications, periodicals → Physics → Biological sciences |
| NPRV | Nitrogen Pressure Relief Valve | In English | |
| NPS | Nonpropulsive Stage | In English | → Spaceflight engineering, astronautics |
| NPS | NASA Planning Studies | In English | → Spaceflight engineering, astronautics |
| NPS | Nuclear Power Station | In English | → Nuclear technology |
| NPSH | Net Positive Suction Head | In English | |
| NPSP | Net Positive Suction Pressure | In English | |
| NPSP | Net Positive Static Pressure | In English | |
| NPSS | NASA Packet Switching System | In English | → Spaceflight engineering, astronautics |
| NPT | Navy Pointer and Tracker | In English | → 359 → Military engineering |
| NPT | Non-Proliferation Treaty | In English | |
| NPU | Nitrogen Purge Unit | In English | |
| NPUJ | Northwestern Polytechnical University Journal | In English | → Serial publications, periodicals → Applied sciences, technology |
| NPV | Nitrogen Pressure Valve | In English | |
| NRAAO | Northeastern Regional Association of Assessing Officers (www.nraao.org) | In English | → Associations → 332 |
| NRALT | NASA Radar Altimeter | In English | → Geodesy, cartography → Spaceflight engineering, astronautics |
| NRAOR | National Radio Astronomy Observatory Reprints | In English | → Serial publications, periodicals → Astronomy |
| NRB | Nuclear Reactor/Brayton | In English | → Nuclear technology |
| NRC | National Research Council | In English | → Research policy |
| NRC | Nitrosso Rubber Coating | In English | |
| NRC | Nonrecurring Costs | In English | → Prices |
| NRC | Nuclear Regulatory Commission | In English | → Nuclear technology |
| NRCC | National Research Council of Canada | In English | → Research policy |
| NRD | National Range Division | In English | |
| NRDS | Nuclear Rocket Development Station | In English | → Nuclear technology → Spaceflight engineering, astronautics |
| NREL | National Renewable Energy Laboratory | In English | → Research institutes → Energy economics |
| NREN | National Research and Education Network | In English | → Networks, communication → Research policy → Education |
| NRF | National Research Foundation | In English | → Foundations → Mathematics and natural sciences → Applied sciences, technology |
| NRFA | Navigation Radio Frequency Assembly | In English | |
| NRFN | National Federation of Retail Newsagents | In English | → Organizations and associations → Trade |
| NRI | Nonrecurring Investment | In English | → Economic policy |
| NRI | Needham Research Institute | In English | |
| NRL | Naval Research Laboratory (www.nrl.navy.mil) | In English | → Research institutes → 359 |
| NRM | Nonrecurring Maintenance | In English | → Maintenance and logistics |
| NRM | New Religious Movement = NMR | Nouveau Mouvement Religieux | In French = NRB | Nieuwe Religieuze Beweging | In Dutch = NRJ | Naujieji religiniai judėjimai | In Lithuanian |
In English | → Modern spiritual movements |
| NRN | National Radio Network | In English | → Telecommunications |
| NRO | National Reconnaissance Organization (www.nro.gov) | In English | → Central administration |
| NRRv | Naval Research Reviews | In English | → Serial publications, periodicals → 6295 → Transport and postal services |
| NRS | Non-conformance Reporting System | In English | |
| NRSC | National Remote Sensing Centre | In English | |
| NRT | Near Real Time | In English | |
| NRTA | Natural Resources Transfer Agreement | In English | |
| NRZ | Nonreturn To Zero | In English | |
| NRZL | Nonreturn-To-Zero Level | In English | |
| NRZPSK | Nonreturn-To-Zero Phase Shift Key | In English | |
| NRZTTL | Nonreturn-To-Zero Transistor-Transistor Logic | In English | |
| NS | Nuclear Shuttle | In English | → Nuclear technology → Spaceflight engineering, astronautics |
| NS | Navier-Stokes | In English | → Physics |
| NS | Nazareth Sisters | In English | → Roman catholic church |
| NSA | Nosewheel Steering Amplifier | In English | |
| NSA | National Security Agency (www.nsa.gov) | In English | → Central administration |
| NSACOR | National Security Agency Central Office of Record | In English | → Public administration, government |
| NSAI | National Standards Authority of Ireland | In English | → Standardization |
| NSAI | National Standard Authority of Ireland | In English | → Organizations and associations → Standardization |
| NSAS | NSTS/SSPE Attachment Systems | In English | |
| NSC | Nonstandard CA Code | In English | |
| NSC | Network Support COmmittee | In English | |
| NSC | Navigational Star Catalog | In English | → Astronomy |
| NSC | NASA Standard Computer | In English | → Hardware → Spaceflight engineering, astronautics |
| NSC | Nepal Study Center | In English | → Organizations and associations → Language, linguistics, literature → Geography, biography, history |
| NSCCA | Nuclear Safety Cross-Check Analysis | In English | → Nuclear technology |
| NSD | NASA Standard Detonator | In English | → Spaceflight engineering, astronautics |
| NSE | Nuclear Science Engineering | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NSE | National Stock Exchange of India | In English | → Finance |
| NSF | National Science Foundation (www.nsf.gov) | In English | → Foundations → Mathematics and natural sciences |
| NSHS | Nosewheel Steering Hydraulic System | In English | |
| NSI | Network Support Item | In English | |
| NSI | NASA Standard Initiator | In English | → Spaceflight engineering, astronautics |
| NSI | NASA Science Internet | In English | → Internet → Spaceflight engineering, astronautics → Astronomy |
| NSI | Nanostructured Surfaces and Interfaces | In English | → Mathematics and natural sciences → Applied sciences, technology |
| NSIA | National Security Industrial Association | In English | → Associations → Military engineering |
| NSIF | Near-Space Instrumentation Facility | In English | → Astronomy → Spaceflight engineering, astronautics |
| NSL | Northrop Space Laboratory | In English | → Research institutes → Astronomy |
| NSLC | National Science Learning Centre | In English | → Education → Mathematics and natural sciences |
| NSLC | Non-Small cell Lung Carcinoma | In English | → Chest diseases → Oncology |
| NSLC | Nova Scotia Liquor Commission | In English | → 64 |
| NSLD | NASA Shuttle Logistics Depot | In English | → Maintenance and logistics → Spaceflight engineering, astronautics |
| NSM | Network Status Monitor | In English | |
| NSMB | Nature Structural & Molecular Biology | In English | → Biological sciences |
| NSN | National Stock Number | In English | |
| NSO | NASA Support Operation | In English | → Spaceflight engineering, astronautics |
| NSO | National Standards Organisation | In English | → Organizations and associations → Standardization |
| NSO | National Solar Observatory | In English | → Observatories → Solar system |
| NSP | Network Signal Processing | In English | → Hardware → Networks, communication |
| NSP | NASA Support Plan | In English | → Spaceflight engineering, astronautics |
| NSP | Network Signal Processor | In English | → Hardware → Networks, communication |
| NSPAR | Nonstandard Part Approval Request | In English | |
| NSpEc | Networks and Spatial Economics | In English | → Serial publications, periodicals → Economics |
| NSS | Network Simulation System | In English | → Networks, communication → Computer simulation |
| NSSA | National Statement of Surveillance Arrangements | In English | |
| NSSCC | NORAD Space Surveillance Computation Center | In English | → Computer science → Astronomy |
| NSSDC | National Space Science Data Center | In English | → Astronomy |
| NSTI | NASA Simulation Traffic Interface | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| NSTL | National Space Technology Laboratories | In English | → Research institutes → Astronomy → Spaceflight engineering, astronautics |
| NSTS | National Space Transportation System | In English | → Spaceflight engineering, astronautics |
| NSTSPO | NSTS Program Office | In English | |
| NSU | Node Switching Unit | In English | |
| NTA | Nusa Tenggara Association | In English | → Associations |
| NTA | National Tax Association | In English | → Associations → Taxes, duties |
| NTA | National Taxidermists Association | In English | → Associations → Zoology |
| NTA | National Television Awards | In English | → Telecommunications |
| NTA | National Tutoring Association | In English | → Associations → Education |
| NTA | National Telecom Agency | In English | → Telecommunications |
| NTA | National Treatment Agency for Substance Misuse | In English | → Personal health and hygiene |
| NTA | National Technology Alliance | In English | → Organizations and associations → Engineering, technology |
| NTA | Nippon Travel Agency | In English | → Tourism |
| NTA | National Trappers Association | In English | → Associations → Fishing, hunting |
| NTA | National Technical Association | In English | → Associations → Applied sciences, technology |
| NTA | National Tour Association | In English | → Associations |
| NTA | Network Timesystem Artner-Rauch | In English | |
| NTC | Nordic Timber Council | In English | → Organizations and associations → Forestry |
| NTCo | Nondestructive Testing Communications | In English | → Serial publications, periodicals → Materials science |
| NTD | NASA Test Director | In English | → Spaceflight engineering, astronautics |
| NTDS | Naval Tactical Data System | In English | → Computer science → 359 |
| NTE | Navigation Telemetry Encoder | In English | → Geodesy, cartography → Vehicle engineering |
| NTF | National Test Facility | In English | |
| NTF | Nigeria Trust Fund | In English | → Financial markets |
| NTIS | National Technical Information Service | In English | → Engineering, technology |
| NTN | New Technology News | In English | → Serial publications, periodicals → Engineering, technology |
| NTNU | National Taiwan Normal University | In English | → Higher education, universities |
| NTPC | Nam Theun 2 Power Company (www.namtheun2.com) | In English | → Electrical engineering |
| NTR | Notifications of Test Results | In English | |
| NTRAC | New Technical Regulations Applications Committee | In English | → Standardization → Engineering, technology |
| NTS | Navigation Technology Satellite | In English | → Spaceflight engineering, astronautics |
| NTS | Near-Term Schedule | In English | |
| NTS | Nonavionics Test Station | In English | |
| NTSC | National Thai Studies Centre | In English | → Area studies |
| NTSC | Nuclear Technology Safety Center | In English | → Nuclear technology |
| NTSC | National Television Standards Committee | In English | → Organizations and associations → Telecommunications |
| NTSO | NASA Test Support Office | In English | → Spaceflight engineering, astronautics |
| NTSS | Nitrogen Transfer and Storage System | In English | |
| NTT | Nippon Telegraph and Telephone (www.ntt.co.jp) | In English | → Telecommunications |
| NTTF | Network Test and Training Facility | In English | |
| NTU | Nanyang Technology University | In English | → Applied sciences, technology → Specialized or (poly)technical colleges |
| NTUA | National Technical University of Athens | In English | → Higher education, universities → Engineering, technology |
| NU | Naresuan University = NU | Naresuan-Universität | In German |
In English | → Higher education, universities |
| NU | Niagara University | In English | → Higher education, universities |
| NU | National University | In English | → Higher education, universities |
| NU | Northeast Utilities | In English | → Energy economics |
| NUA | Network User Address | In English | → Networks, communication |
| NUA | Net Unrealized Appreciation | In English | → Finance |
| NUAAJ | Nanjing University Aeronautics and Astronautics Journal | In English | → Serial publications, periodicals → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| NuAlg | Numerical Algorithms | In English | → Serial publications, periodicals → Mathematics |
| NucFS | Nuclear Fusion Special Supplement | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NucFu | Nuclear Fusion | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NucIM | Nuclear Instruments and Methods | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NucPh | Nuclear Physics | In English | → Serial publications, periodicals → Nuclei |
| NucTe | Nuclear Technology | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NucTF | Nuclear Technology Fusion | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NUDET | Nuclear Detonation | In English | → Nuclear technology → Military engineering |
| NUDTJ | National University Defense Technology Journal | In English | → Serial publications, periodicals → Military engineering |
| NuEnD | Nuclear Engineering and Design | In English | → Serial publications, periodicals → Nuclei → Nuclear technology |
| NUFEM | Nagoya University Faculty Engineering Memoirs | In English | → Serial publications, periodicals → Engineering, technology |
| NuGeo | Nuclear Geophysics | In English | → Serial publications, periodicals → Nuclei → Geophysics |
| NUL | Non-GSE Utilization List | In English | |
| NuMat | Numerische Mathematik | In English | → Serial publications, periodicals → Computer-based techniques → Mathematics |
| NURBS | Non-Uniform Rational B-splines | In English | → Graphical processing → Image processing → Cinema, movies |
| NUS | National University of Singapore | In English | → Higher education, universities |
| NUSEM | Nagoya University School Engineering Memoirs | In English | → Serial publications, periodicals → Engineering, technology |
| NUSS | NUclear Safety Standards | In English | → Nuclear technology |
| NUT | National Union of Teachers | In English | → Organizations and associations → Labour, labour economics → Education |
| NUTI | NASCOM User Traffic Interface | In English | |
| NUTS | Nomenclature of Territorial Units for Statistics | In English | → International relations → Regional planning |
| NV | Nuclear Vehicle | In English | → Nuclear technology → Vehicle engineering |
| NV | NASA Altimeter Verification | In English | → Spaceflight engineering, astronautics |
| NVAFB | North Vandenberg Air Force Base | In English | → 358 → Aeronautics, aircraft |
| NVCA | National Venture Capital Association (www.nvca.org) | In English | → Associations → 33676 |
| NVE | Nonvisual Eyepiece | In English | |
| NVEOL | Night Vision and Electro-Optical Laboratory | In English | → Research institutes |
| NVLAP | National Voluntary Laboratory Accreditation Programme | In English | |
| NVM | Nonvolatile Memory | In English | → Memories |
| NVQ | National Vocational Qualification | In English | → Specialized or (poly)technical colleges |
| NVR | NASA Waiver | In English | → Spaceflight engineering, astronautics |
| NWCI | National Women's Council of Ireland | In English | → Organizations and associations → Feminism |
| NWE | Nuclear Weapons Effect | In English | → Nuclear technology → Military engineering |
| NWG | Natural Work Group | In English | |
| NWMP | Nuclear Weapons Monitor Plan | In English | → Nuclear technology → Military engineering |
| NWP | Netherlands Water Partnership | In English | → Organizations and associations → Hydrology → Environmental technology, water supply, waste management |
| NWS | Nosewheel Steering | In English | |
| NWS | National Weather Service | In English | → Meteorology, climatology |
| NWSA | Nosewheel Steering Amplifier | In English | |
| NYASA | New York Academy Sciences Annals | In English | → Serial publications, periodicals → Mathematics and natural sciences |
| NYCAS | New York Conference on Asian Studies | In English | → Area studies |
| NYCCS | New York Center for Computational Science | In English | → Computer science → 5196 |
| NYSAFLT | New York State Association of Foreign Language Teachers (www.nysaflt.org) | In English | → Associations → Education → Language, linguistics, literature |
| NYSE | New York Stock Exchange | In English | → Financial markets |
| NYU | New York University (www.nyu.edu) | In English | → Higher education, universities |
| NZASIA | New Zealand Asian Studies Society | In English | → Area studies |
| NZDL | New Zealand Digital Library Project | In English | → Libraries → Area studies |
| NZFA | New Zealand Flag Association | In English | → Associations → 9299 |
| NZJAS | New Zealand Journal of Asian Studies | In English | → Serial publications, periodicals → Area studies |
| NZJGG | New Zealand Journal Geology and Geophysics | In English | → Serial publications, periodicals → Earth sciences → Geophysics |
| NZJS | New Zealand Journal of Science | In English | → Serial publications, periodicals → Mathematics and natural sciences |
| O | Oxygen = O | Oxygène | In French = O | Suurstof | In Afrikaans = O | Sauerstoff | In Tosk = O | أكسجين | In Arabic = O | Oxíxenu | In Asturian = O | Oksigen | In Azerbaijani = O | Sauastoff | In Austro-Bavarian = O | Кісларод | In Belarusian = O | Кислород | In Bulgarian = O | অক্সিজেন | In Bengali = O | Oksigen | In Breton = O | Kiseonik | In Bosnian = O | Oxigen | In Catalan = O | Ossigenu | In Corsican = O | Kyslík | In Czech = O | Йӳçлĕк | In Chuvash = O | Ocsigen | In Welsh = O | Ilt | In Danish = O | Sauerstoff | In German = O | Οξυγόνο | In Greek = O | Oksigeno | In Esperanto = O | Oxígeno | In Spanish = O | Hapnik | In Estonian = O | Oxigeno | In Basque = O | اکسیژن | In Persian = O | Happi | In Finnish = O | Ossigjen | In Friulian = O | Soerstof | In Frisian = O | Ocsaigin | In Irish = O | Àile-beatha | In Scottish Gaelic = O | Osíxeno | In Galician = O | ઑક્સીજન | In Gujarati = O | Ocsygien | In Manx = O | חמצן | In Hebrew = O | आक्सीजन | In Hindi = O | Kisik | In Croatian = O | Kislik | In Upper Sorbian = O | Oksijèn | In Haitian Creole = O | Oxigén | In Hungarian = O | Թթվածին | In Armenian = O | Oxygeno | In Interlingua = O | Oksigen | In Indonesian = O | Oxo | In Ido = O | Súrefni | In Icelandic = O | Ossigeno | In Italian = O | 酸素 | In Japanese = O | kijno | In Lojban = O | Oksigen | JV = O | ჟანგბადი | In Georgian = O | ಆಮ್ಲಜನಕ | In Kannada = O | 산소 | In Korean = O | Sauerstoff | In Kölsch = O | Oksîjen | In Kurdish = O | Oxygenium | In Latin = O | Sauerstoff | In Letzeburgesh = O | Zuurstof | In Limburgish = O | Oksijɛ́ní | In Lingala = O | Deguonis | In Lithuanian = O | Skābeklis | In Latvian = O | Hāora | In Māori = O | Кислород | In Macedonian = O | ഓക്സിജന് | In Malayalam = O | Хүчилтөрөгч | In Mongolian = O | ऑक्सिजन | In Marathi = O | Oksigen | In Malay = O | Ehēcayoh | En Nahuatl = O | Suerstoff | In Low German = O | अक्सिजन | In Newari (Nepal Bhasa) = O | Zuurstof | In Dutch = O | Oksygen | In Nynorsk = O | Oksygen | In Norwegian = O | Oxygen | In Oromo = O | Oxygen | In Kapampangan = O | Tlen | In Polish = O | Oxigénio | In Portuguese = O | Muksichaq | In Quechua = O | Oxigen | In Romanian = O | Кислород | In Russian = O | Ossìgginu | In Sicilian = O | Kiseonik | In Serbo-Croatian = O | ඔක්සිජන් | In Sinhalese = O | Kyslík | In Slovak = O | Kisik | In Slovenian = O | Oksigjeni | In Albanian = O | Кисеоник | In Serbian = O | Oksigén | In Sundanese = O | Syre | In Swedish = O | Oksijeni | In Swahili = O | ஆக்ஸிஜன் | In Tamil = O | ఆక్సిజన్ | In Telugu = O | Оксиген | In Tajik = O | ออกซิเจน | In Thai = O | Oksiheno | In Tagalog = O | Oksijen | In Turkish = O | Кисень | In Ukrainian = O | Kislorod | In Uzbek = O | Ôxy | In Vietnamese = O | זויערשטאף | In Yiddisch = O | 氧 | In Chinese |
In English | → Chemistry |
| OAA | Orbiter Access Arm | In English | → Spaceflight engineering, astronautics |
| OAA | ORU Alternative Analysis | In English | |
| OAA | Orbiter Alternate Airfield | In English | → Spaceflight engineering, astronautics |
|