| NAC | acetylcysteine |
| NADC | non-AIDS-defining cancer |
| NaF | sodium fluoride |
| NAFLD | nonalcoholic fatty liver disease |
| NAP | neutrophil activation probe imaging agent |
| NASH | nonalcoholic steatohepatitis |
| NBCCS | basal cell nevus syndrome; Gorlin syndrome; nevoid basal cell carcinoma syndrome |
| NBI-3001 | interleukin-4 PE38KDEL cytotoxin; interleukin-4 PE38KDEL immunotoxin |
| NCCIH | National Center for Complementary and Integrative Health |
| NCI | National Cancer Institute |
| NCS | zinostatin |
| NCTN | National Clinical Trials Network |
| NDGA | masoprocol; Actinex; nordihydroguaiaretic acid |
| NDV | Newcastle disease virus |
| NEIAED | non-enzyme-inducing antiepileptic drug |
| NES | neuromuscular electrical stimulation; therapeutic (subthreshold) electrical stimulation |
| NESP | darbepoetin alfa |
| NF1 | neurofibromatosis type 1 |
| NF2 | acoustic neurofibromatosis; neurofibromatosis type 2 |
| NFE2L2 | Nrf2; nuclear factor (erythroid-derived 2)-like 2 |
| NF-kB | NF-kappa B; nuclear factor-kappa B |
| NGR-TNF | CNGRC peptide-TNF alpha conjugate; tumor vasculature-targeted tumor necrosis factor alpha |
| NGS | massively parallel sequencing; next-generation sequencing |
| NHL | non-Hodgkin lymphoma |
| NIC | nicotine |
| NiCE | nitroglycerin/sodium citrate/ethanol solution |
| NIH | National Institutes of Health |
| NILM | negative for intraepithelial lesion; malignancy; negative Pap test result; normal Pap test result |
| NIMO | nimodipine |
| NIVO | nivolumab |
| NK-LGL | natural killer cell; NK cell |
| NK-LGLL | natural killer-cell large granular lymphocyte leukemia; NK-LGL leukemia |
| NLPHL | nodular lymphocyte-predominant Hodgkin lymphoma |
| NLST | National Lung Screening Trial |
| NMA | tilarginine |
| NMC | methylcantharidimide |
| NMES | neuromuscular electrical stimulation; therapeutic (subthreshold) electrical stimulation |
| NMF | N-methylformamide |
| NMHE | elliptinium acetate |
| NMP22 | nuclear matrix protein 22 |
| NMRI | nuclear magnetic resonance imaging |
| NMS | neuroleptic malignant syndrome |
| NP | advanced practice nurse; nurse practitioner |
| NPe6 | talaporfin sodium |
| NPV | negative predictive value |
| NR | nicotinamide riboside |
| NSAID | nonsteroidal anti-inflammatory drug |
| NSCLC tumor antigen-loaded Dex | NSCLC antigen-loaded dendritic cell-derived exosomes |
| NTX-010 | Seneca Valley virus-001 |
| NVB | vinorelbine tartrate |
| NVP | nevirapine |
| NX211 | liposomal lurtotecan |