| Acronym | Meaning |
| NBACC | National Biodefense Analysis And Countermeasures Centerpa |
| NBC | Nuclear, Biological And Chemical |
| NBD | Nucleotide Binding Domain |
| NBFAC | National Bioforensic Analysis Center Par |
| NBI | Neutral Beam Injection |
| NBII | National Biological Information And Infrastructure |
| NBMO | Nonbonded Molecular Orbital |
| NBO | Natural Bond Order |
| NBOD | Nitrogenous Biochemical Oxygen Demand |
| NBR | Nitrile-butadiene Rubber |
| NBRF | National Biomedical Research Foundation |
| NBS | National Bureau Of Standards |
| NBS | Nijmegen Breakage Syndrome |
| NBS | Nuclear Backscattering Spectroscopy |
| NBS | Nucleotide-binding Site |
| NBSB | National Biomonitoring Specimen Bank |
| NBSR | Neutron Beam Split-core Reactor |
| NC-IUBMB | Nomenclature Committee Of The International Union Of Biochemistry And Molecular Biology |
| NCAC | Nitrogen-containing Aromatic Compound |
| NCAM | Neural Cell Adhesion Molecule |
| NCAP | Nematic Curvilinear Aligned Phase |
| NCAP | Noncriteria Air Pollutants |
| NCAR | National Center For Atmospheric Research (USA) |
| NCASI | National Council For Air And Stream Improvement |
| NCAT | National Catalog Database (accessible Through OLS) |
| NCB | National Coal Board |
| NCBI | National Center For Biotechnology Information |
| NCC | National Computing Center |
| NCC | Near-centerline Concn. |
| NCCAM | National Center For Complementary And Alternative Medicine |
| NCCCS | Northern California Coastal Circulation Study |
| NCCLS | National Committee For Clinical Laboratory Standards |
| NCDC | National Climatic Data Center |
| NCDGF | Noncalcareous Dark Grey Floodplain |
| NCDS | NASA Climate Data System |
| NCE | New Chemical Entity |
| NCEA | National Center For Environmental Assessment |
| NCEH | National Center For Environmental Health |
| NCEP | National Centers For Environmental Prediction |
| NCEP | National Cholesterol Education Program |
| NCFLG | Near-critical Fluids And Liquefied Gases |
| NCHGR | National Center For Human Genome Research |
| NCHS | National Center For Health Statistics |
| NCI | National Cancer Institute |
| NCID | National Center For Infectious Diseases |
| NCLAN | National Crop Loss Assessment Network |
| NCLAP | National Crop Loss Assessment Program |
| NCLI | National Chemical Laboratory For Industry (Japan) |
| NCMET | Nonclosed Shell Many Electron Theory |
| NCMS | National Center Manufacturing Sciences |