| Abbreviation | Definition |
|---|---|
| NPTL | Natural Products Training Laboratory |
| NPTL | Neural Prosthetics Translational Laboratory |
| NPV | Nuclear Polyhedrosis Virus |
| NR | no reaction |
| NRC | Nutritional Research Committee |
| NREAC | Nonreactive |
| NREL | National Renewable Energy Laboratory |
| NREL | Natural Resource Ecology Laboratory |
| NREL | Neuromuscular Rehabilitation Engineering Laboratory |
| NRL | National Radiation Laboratory |
| NRL | National Research Laboratory |
| NRR | National Research Register |
| NRR | UK National Research Register |
| NRRL | NeuroRehabilitation Research Laboratory |
| NRS | Normal Rabbit Serum |
| NRS | Northern Research Station |
| NRTL | National Recognized Testing Laboratories |
| NRTL | Nationally Recognised Testing Laboratories |
| NRTL | Nationally Recognised Testing Laboratory |
| NRTL | Nationally Recognized Test Laboratory |