| Acronym | Meaning |
| NMAM | NIOSH Manual Of Analytical Methods |
| NMC | New Muon Collaboration |
| NMCSCF | Numerical Multiconfiguration Self-consistent Field |
| NMDAR | N-methyl-D-aspartate Receptor |
| NMDR | Nuclear Magnetic Double Resonance |
| NMDS | Nonmetric Multidimensional Scaling |
| NME | New Molecular Entity |
| NMEP | National Materials Exposure Programme |
| NMFS | National Marine Fisheries Service (of NOAA) |
| NMHC | Nonmethane Hydrocarbons |
| NMI | Nautical Miles |
| NMIJ | National Metrology Institute Of Japan |
| NMJ | Neuromuscular Junction |
| NMMAPS II | The National Morbidity |
| NMMO | N-methylmorpholine N-oxide |
| NMMSS | Nuclear Materials Management And Safeguards System |
| NMN | Nicotinamide Mononucleotide |
| NMO | Natural Magnetic Orbital |
| NMOC | Nonmethane Organic Compound(s) |
| NMOG | Non-Methane Organic Gases |
| NMOS | Negative Channel Metal-oxide Semiconductor |
| NMP | Nitroxide-mediated Polymerization |
| NMP | Nuclear Microprobe |
| NMPIMC | Normal Mode Path Integral Monte Carlo |
| NMR | Nuclear Magnetic Resonance |
| NMRD | Nuclear Magnetic Relaxation Dispersion |
| NMRI | Nuclear Magnetic Resonance Imaging |
| NMSC | Non-melanoma Skin Cancer |
| NMVOC | Nonmethane Volatile Organic Compound |
| NN-TB | Nearest-neighbor Tight Binding |
| NNBI | Neglect Of Nonbonded Interactions |
| NND | New And Nonofficial Drugs |
| NNDC | National Nuclear Data Center |
| NNDO | Neglect Of Nonbonded Differential Overlap |
| NNI | National Nanotechnology Initiative |
| NNLO | Next-to-next-to-leading Order |
| NNLS | Non-negative Least-squares |
| NNRTI | Non-nucleoside Reverse Transcriptase Inhibitor |
| NNSA | National Nuclear Security Administration |
| NO | Natural Orbital |
| NOAA | National Oceanic And Atmospheric Administration |
| NOAEL | No Observable Adverse Effect Level |
| NOAO | National Optical Astronomy Observatories |
| NOBIC | Near-field Optical Beam Induced Current |
| NOC | Nonionic Organic Contaminants |
| NOD | Nitrogenous Oxygen Demand |
| NOD | Nonobese Diabetic |
| NODA | Notice Of Data Availability |
| NODC | National Oceanographic Data Center (Washington |
| NODP | National Oceanic And Deposition Program |