| Abbreviation | Definition |
|---|---|
| NFU | Non-Fissile U |
| NG | Noble Gas |
| NGL | Natural Gas Liquid |
| NGS | Nitrogen Gas System |
| NH | Nitrogen |
| NH | No Headstone |
| NH | No Humedad (Non-Humidity) |
| NH2 | amidogen |
| Nh3 | Ammonia gase |
| NH4+ | Ammonium (not an acronym) |
| NHC | N Heterocyclic Carbene |
| NHCL | National Historic Chemical Landmark |
| NHCL | National Historic Chemical Landmarks |
| NHE | Normalized Hydrogen Electrode |
| NHPI | N-Hydroxyphthalimide |
| NI | Nematic Isotropic |
| Ni | Nickel |
| NIB | Neodymium Iron Boron |
| NICAD | NIckel CADmium |
| NICS | Nucleus Independent Chemical Shift |