| Acronym | Meaning |
| NTB | Nonorthogonal Tight-binding |
| NTCF | National Toxics Campaign Fund |
| NTD | Neutron Transmutation Doping |
| NTD | Nuclear Track Detector |
| NTDB | National Trade Databank |
| NTEF | Near Total External Fluorescence |
| NTGS | Air/Superfund National Technical Guidance Study |
| NTI | National Toxics Inventory |
| NTI | Negative Thermal Ionization (for Mass Spectrometry) |
| NTIAC | Nondestructive Testing Information Analysis Center |
| NTIMS | Negative Thermal Ionization Mass Spectrometry |
| NTIS | National Technical Information Service |
| NTN | National Trends Network |
| NTNCWS | Nontransient, Noncommunity Water Supplies |
| NTO | Natural Transition Orbital Method (for Excited States) |
| NTP | National Toxicology Program |
| NTP | Normal Temperature And Pressure |
| NTR | Nontranslated Region |
| NTRM | NIST Traceable Ref. Materials |
| NTRS | National Technology Roadmap For Semiconductors |
| NTS | Nevada Test Site |
| NTS | Nucleus Of The Solitary Tract |
| NTSB | National Transportation Safety Board |
| NTTAA | National Technology Transfer And Advancement Act |
| NTTC | National Technical Transfer Center |
| NTU | Nephelometric Turbidity Unit |
| NTU | Number Of Transfer Units (in Packed Tower Aeration System) |
| NUCEF | Nuclear Fuel Cycle Safety Engineering Research Facility |
| NUR | Nitrate Utilization Rate |
| NURE | National Uranium And Resource Evaluation |
| NURP | Nationwide Urban Runoff Program (USEPA) |
| NURSA | Nuclear Receptor Signaling Atlas |
| NVDOC | Non-volatile Dissolved Organic Carbon |
| NVFEL | National Vehicle And Fuel Emissions Laboratory |
| NVFRAM | Nonvolatile Ferroelectric Random Access Memory |
| NVH | Noise, Vibration, And Harshness |
| NVLAP | National Voluntary Laboratory Accreditation Program |
| NVM | Non-volatile Memory |
| NVP | Newton Variational Principle |
| NVPA | No-virtual-pair Approxn. |
| NVR | Non-volatile Residue |
| NVSM | Nonvolatile Semiconductor Memory |
| NVSS | NRAO VLA Sky Survey |
| NWC | National Water Council (UK) |
| NWEA | National Wood Energy Association |
| NWIS | Nuclear Weapons Identification System |
| NWPA | Nuclear Waste Policy Act |
| NWQMC | National Water Quality Monitoring Council |
| NWR | National Wildlife Refuge |
| NWR | Normotensive Wistar Rat |