| Abbreviation | Definition |
|---|---|
| NNO | National Network Office |
| NNP | Nuclear Non-Proliferation |
| NNPT | Nuclear Non-Proliferation Treaty |
| NNRD | Nemaha Natural Resources District |
| NNSA | National Nuclear Security Administration |
| NNSGRC | National Newborn Screening and Genetics Resource Center |
| NNSP | National Nuclear Security Plan |
| NOA | Not Otherwise Approved |
| NOAEL | no-observed-adverse-effect-level |
| NOAEL | no-observed-adverse-effects-level |
| NOAO | National Optical Astronomy Observatory |
| NOC | National Occupational Classification |
| NOC | National Occupational Code |
| NOC | National Olympic Committee |
| NOC | Non Official Cover |
| NOC | Not Our Citizen |
| NOC | Notice Of Commencement |
| NOD | Notice Of Default |
| NODA | Notice Of Data Availability |
| NODC | National Oceanographic Data Center |