| NA | North America or North American |
| NA | Notice of Allowance (Patents) |
| NAA | N-Acetylaspartate |
| NAA | Naphthalene Acetic Acid |
| nAChR | Nicotinic Acetyl Choline Receptor |
| NAD | Nicotinamide Adenine Dinucleotide |
| NAD | Non Aq. Dispersion |
| NADA | New Animal Drug Application |
| NADH | Nicotinamide Adenine Dinucleotide Hydrogenated. |
| NAE | NEDD8-Activating Enzyme |
| NAF | Neuronal Attachment Factor |
| NAION | Non-arteritic Anterior Ischemic Optic Neuropathy |
| NAIST | NAra Institute of Science & Technology (Japan) |
| NAMPRT | NicotinAMide PhosphoRibosyl Transferase (Oncology) |
| NAO | Normal Alpha Olefin |
| NAP | Nematode Anticoagulant Protein |
| NAPU | Network Addressable Processing Unit |
| NARI | Nor Adrenaline Reuptake Inhibitors |
| NAS | N Acetyl Serotonin |
| NAS Steroi | NeuroActive Steroid |
| NASA | National Aeronautics & Space Administration (USA Government) |
| NASBA | Nucleic Acid Sequence Base Amplification |
| NASH | Non Alcoholic Steato Hepatitis |
| NAT | Nucleic Acid Tests |
| NATA | National-scale Air Toxics Assessment (USA - EPA) |
| NATO | North Atlantic Treaty Organization |
| NBC | Niacin Bound Chromium |
| NBE | New Biological Entities |
| NBI | Narrow Band Imaging |
| NBR | Nitrile Butadiene Rubber |
| NCA | N (nitrogen) Carboxy Anhydride |
| NCA | Non Coordinating Anion |
| NCAUR | National Center for Agricultural Utilization Research (USDA) |
| NCBI | National Center for Biotechnology Information (U.S.A. Government) |
| NCCN | National Comprehensive Cancer Network |
| NCE | New Chemical Entity |
| NCG | non-condensable gas |
| NCI | National Cancer Institute (USA) |
| NCL | Neutrophil Chemotactic Lymphokine |
| NCMC | NIST (Abbrev.) Combinatorial Methods Center |
| NCP | Non Cancer Pain |
| ncRNA | non coding RNA |
| NCT | N-Chloro Taurine |
| ND | Newcastle Disease |
| Nd-PBR | Neodymium Poly Butadiene Rubber |
| NDA | Naphthalene Dicarboxylic Acid |
| NDA | New Drug Application (FDA) |
| NDGA | Nor Dihydro Guaiaretic Acid |
| NDO | Neurogenic Detrusor Overactivity |
| NDPA | Nitro Di Phenyl Amine |
| NDPK | Nucleoside Di Phosphate Kinase |
| NDRI | Norepinephrine & Dopamine Reuptake Inhibitors |
| NDT | non destructive testing |
| NE | Neutrophil Elastase |
| NE | Netherlands |
| NEC | National Economic Council (USA) |
| NECAR | New Electric CAR |
| NED | No Evidence of Disease |
| NEI | Neutrophil Elastase Inhibitor |
| NEI Onco. | Nuclear Export Inhibitors |
| NEJM | New England Journal of Medicine |
| NEMS | Nano Electro Mechanical Systems |
| NER | Nucleotide Excision Repair (Oncology) |
| NES | Normal Epithelial Specific protein |
| NET | Neuro Endocrine Tumors |
| NET Hemato | neutrophil extracellular trap |
| NEXAFS | Near Edge X-ray Absorption Fine Structure |
| NF | Nitro Furazone (Antibiotics) |
| NfL Neuro. | Neuro filament Light chain |
| NFPA | National Food Processors Association (USA) |
| NFT | non-fungible tokens |
| NG | Non Generic |
| NGAL | Neutrophil Gelatinase-Associated Lipocalin |
| NGF | Nerve Growth Factor |
| NGS | next generation sequencing |
| NHC | N Heterocyclic Carbene |
| NHGRI | National Human Genome Research Institute (USA - NIH) |
| NHL | Non Hodgkins Lymphoma |
| NHMFL | National High Magnetic Field Laboratory |
| NHPI | N-Hydroxy Phthal Imide |
| NHS | N-Hydroxyl Sulfosuccinimide |
| NIAID | National Institute of Allergy & Infectious Diseases (NIH; USA) |
| NIAMS | National Institute of Arthritis & Musculoskeletal & Skin (USA - NIH) |
| NIBIB | National Institute of Biomedical Imaging & Bioengineering (USA - NIH) |
| NIBR | Novartis Institute of Biomedical Research (USA) |
| NICE | National Institute for health and Clinical Excellence |
| NICNAS | NATIONAL INDUSTRIAL CHEMICALS NOTIFICATION AND ASSESSMENT SCHEME (Australian Gov.) |
| NICU | Neonatal Intensive Care Unit |
| NIDCR | National Institute of Dental & Craniofacial Research (NIH) |
| NIDDM | Non Insulin Dependent Diabetes Mellitus |
| NIEHS | National Institute of Environmental Health Sciences (USA>NIH) |
| NIF | Neutrophil Inhibitory Factor |
| NIGMS | National Institute of General Medical Sciences [USA - (NIH)] |
| NIH | National Institutes of Health (USA Government) |
| NIMH | National Institute of Mental Health (USA - NIH) |
| NIMS | National Institute for Materials Science (Japan) |
| NIOSH | National Institute for Occupational Safety & Health (USA) |
| NiPhC | Nickel Phthalo Cyanine (dye) |
| NIPPV | Non Invasive Positive-Pressure Ventilation |
| NIR | Near Infra Red |
| NIRS | Near Infra Red Spectroscopy |
| NIST | National Institute of Standards & Technology (Commerce Dept.; USA) |
| NIT | 2-n-Nonyl Iso Thiazolin-3-one (Biocide) |
| NIV | Non Invasive Ventilation |
| NJNC | New Jersey Nanotechnology Consortium |
| NK | Neuro Kinin |
| NK | Natural Killer (immunology; lymphocytes) |
| NKEFB | Natural Killer cell Enhancing Factor B |
| NKT | NK T cell modulators |
| NL | Nano Lithography |
| NL | NetherLands |
| NLG | Natural Language Generation |
| NLM | National Library of Medicine (U.S.A. Government) |
| NLO | Non Linear Optical |
| NMA | N-Methylol Acrylamide |
| NMB | Neuro Muscular Blockade |
| NMBA | Non-depolarizing neuroMuscular Blocking Agent |
| NMC | Ni Mn Co |
| NMDA | N Methyl D Aspartate |
| NMDAR | N-Methyl-D-Aspartate Receptor |
| nmDBMD | Nonsense Mutation Duchenne/Becker Muscular Dystrophy |
| NME | New Molecular Entity (Pharma.) |
| NMIBC | non-muscle invasive bladder cancer |
| NMJ | NeuroMuscular Junction |
| NMOS | N - type Metal Oxide Semiconductor |
| NMP | Non Metal Product |
| NMP | Nitroxide Mediated Polymn. (Living controlled polymn.) |
| NMP | Nuclear Matrix Protein |
| NMP | N-Methyl Pyrrolidone |
| NMPA | National Medical Products Administration (CN) |
| NMR | Nuclear Magnetic Resonance |
| nMSC | neonatal Mesenchymal Stem Cells |
| NNI | National Nanotechnology Initiative (USA Government) |
| NNR | Neuronal Nicotinic Receptors |
| NNRTI | Non Nucleoside Reverse Transcriptase Inhibitor |
| NO | Nitric Oxide |
| NO | NOrway |
| NOA | Notice Of Allowance |
| NOBS | Nonanoyl Oxy Benzene Sulfonate |
| NOEL | No Observable-Effects Level |
| NOH | Neurogenic Orthostatic Hypotension |
| NOI | Notice of Intention |
| NOP | Naso-OroPharyngeal |
| NOS | Nitric Oxide Synthase |
| NOS | Nitrogen oxide Overproduction Syndrome |
| NOS | Nitrogen oxide Overproduction Syndrome |
| NP | NasoPharyngeal |
| NPA | Notice of Patent Allowance |
| NPB | n Pr Bromide |
| NPC | Nuclear Pore Complex |
| NPC | Niemann Pick C (disease) |
| NPC Onco. | Naso Pharyngeal Carcinoma |
| NPCA | National Paint & Coatings Association (USA) |
| NPCM | Non-PHA Cell Material |
| NPD | New Product Development |
| NPDR | Non-Proliferative DR |
| NPE | Nonyl Phenol Ethoxylate |
| NPG | Neo Pentyl Glycol |
| NPH | Neutral Protamine Hagedorn |
| NPI | Non Polarity Index (Ester Lubricants) |
| NPLS | Non Patent Literature Source |
| NPM | Nucleo Phosmin protein Mutants |
| NPN | Non Protein Nitrogen |
| NPRA | Natriuretic Peptide Receptor A |
| NPT | Nanosphere Preconcentrate Technology |
| NPU | Neural Processing Unit |
| NPWT | Negative Pressure Wound Therapy |
| NPY | Neuro Peptide Y |
| NR | Natural Rubber |
| NRAMP | Natural Resistance Associated Macrophage Protein |
| NRAS | Neuroblastoma RAS |
| NRC | National Research Council |
| NREL | National Renewable Energy Laboratory (USA's Dept. of Energy) |
| NRP | Non-Ribosomal Peptide |
| NRPS | Non Ribosomal Peptide Synthetase |
| NRTI | Nucleoside Reverse Transcriptase Inhibitor |
| NRU | Nitrogen Recovery Unit |
| NS | Non Structural (Protein) |
| NSAID | Non - Steroid Anti - Inflammatory Drugs |
| NSCLC | Non Small Cell Lung Cancer |
| NSF | National Science Foundation |
| NSRI | Norepinephrine Serotonin Reuptake Inhibitors |
| NSTC | National Science & Technology Council (USA) |
| NSTE | Non ST Elevation (Cardiology) |
| NSTEMI | Non-ST-segment Elevation Myocardial Infarction |
| NT | Neuro Trophin |
| NT | Neuro Tensin |
| NT Pro BNP | N-Terminal Pro-B-type Natriuretic Peptide |
| NTA | Nitrilo Tri Acetate |
| NTA | Non Transparent Automotive (trim uses) |
| NTDDS | Nerve Targeted Drug Delivery System |
| NTE | Negative-Thermal-Expansion |
| NTF | Neuro Trophic Factor |
| NTM | Non Tuberculous Mycobacterium |
| NTP | National Toxicology Program [Dept Health & Human Services (USA)] |
| NTP | Nano Transfer Printing (Electronics) |
| NTP | Neural Thread Protein (Alzheimers Disease) |
| NTR | Nicotinamide adenine dinucleotide phosphate Thioredoxin Reductase |
| NTR | Non Translated Region (gene engineering) |
| NTSB | National Transportation Safety Board (U.S.A.) |
| NUTI | Nosocomial Urinary Tract Infection |
| NVAF | non-valvular atrial fibrillation |
| NVH | Noise, Vibration & Harshness |
| NVP | N-Vinyl Pyrrolidone |
| NW | Non Woven |
| NYHA | New York Heart Association |
| NYLS | Navy Yoelii Liver Stage (Malaria) |
| NYSE | New York Stock Exchange |