| Acronym | Meaning |
| CMT | Computed Microtomography |
| CMU | Condition Monitoring Unit |
| CMV | Cucumber Mosaic Virus |
| CMX | Connected-moments Expansion |
| CMX(2) | Second-order Connected Moments Expansion (method For Calcg. Correlation Energies Of Mols.) |
| CMZP | Calcium Magnesium Zirconium Phosphate |
| CN | Cellulose Nitrate |
| CN | Condensation Nucleus |
| CNAEL | Committee On National Accreditation Of Environmental Laboratories (US EPA) |
| CNC | Computer Numerical Control |
| CNC | Condensation Nucleus Counter |
| CND | Circumnuclear Disk |
| CNDO | Complete Neglect Of Differential Overlap |
| CNDO LHP | Complete Neglect Of Differential Overlap Longet-Higgins-Pople |
| CNDO SP | Complete Neglect Of Differential Overlap Spin Polarization |
| CNDO/2-FA | Complete Neglect Of Differential Overlap First Approxn. |
| CNDO/2-FPP | Complete Neglect Of Differential Overlap With Finite Perturbation And Polarization |
| CNDO/2-U | Universal CNDO/2 (extended To Full Periodic Table) |
| CNDO/2-V | Complete Neglect Of Differential Overlap-potential Method |
| CNDO/2D | Complete Neglect Of Differential Overlap With Deorthogonalization |
| CNDO/B | Complete Neglect Of Differential Overlap / Boyd |
| CNDO/BW | Complete Neglect Of Differential Overlap With Boyd And Whitehead Parametrization |
| CNDO/F | Complete Neglect Of Differential Overlap/force |
| CNDO/FK | Complete Neglect Of Differential Overlap/ Fischer-Kollmar |
| CNDO/IP | Complete Neglect Of Differential Overlap/ionization Potential |
| CNDO/OPTIC | CI Method For Elec. Transition Moments Of The Optical Transition Of Large Mols. Based On CNDO/S Parametrization |
| CNDO/S | Complete Neglect Of Differential Overlap/spectroscopic |
| CNDO/SW | Complete Neglect Of Differential Overlap / Sichel-Whitehead |
| CNDO/SWW | Complete Neglect Of Differential Overlap/ Sichel-Whitehead-Wratten Parametrization |
| CNDOL | Complete Neglect Of Differential Overlap-azimutal Quantum Number (of Valence AO'S) |
| CNDP | Cold Neutron Depth Profiling |
| CNES | Centre National D'Etudes Spatiales (French Space Center) |
| CNG | Compressed Natural Gas |
| CNIDR | Clearinghouse For Networked Information Discovery And Retrieval |
| CNIE | Committee For The National Institute For The Environment |
| CNLS | Complex Nonlinear Least Squares (data Fitting Method) |
| CNLSD | Condensation Nucleation Light Scattering Detection |
| CNMMN | Commission On New Minerals And Mineral Names |
| CNN | Computational Neural Network |
| CNO | Constrained Nonorthogonal Orbital (algorithm) |
| CNOC | Commission On Nomenclature Of Organic Chemistry |
| CNP | C-type Natriuretic Peptide |
| CNPGAA | Cold Neutron Prompt Gamma-ray Activation Analysis |
| CNPPA | Commission On National Parks And Protected Areas |
| CNRF | Cold Neutron Research Facility |
| CNRS | Centre Nationale De La Recherche Scientifique (France) |
| CNS | Central Nervous System |
| CNT | Carbon Nanotube |
| CNTD | Chemical Nucleated Thermal Deposition |
| CNTF | Ciliary Neurotrophic Factor |