| Acronym | Meaning |
| COOP | Crystal Orbital Overlap Population |
| COP | Cyclic Olefin Polymers |
| COP | Crystal Originated Particle |
| COP | Coefficient Of Performance |
| COPC | Contaminants Of Potential Concern |
| COPD | Chronic Obstructive Pulmonary Disease |
| COPE | Cytokines Online Pathfinder Encyclopaedia |
| COPM | Carter Ozone Per Mile |
| COPNA | Condensed Polynuclear Aromatics |
| COPW | Complete Orthogonalized Plane Wave |
| CORAL | Control Retrofit Assessment Library [EPRI Software] |
| CORBA | Common Object Request Broker Architecture |
| CORC | Cooperative Online Resource Catalog |
| CORDIS | Community Research And Development Information Service |
| CORE | Comprehensive Risk Evaluation |
| CORMA | COmplete Relaxation Matrix Analysis |
| CORMIX | Cornell Mixing Zone Model |
| CORR | Chemicals On Reporting Rules |
| COS | Cosmic Origins Spectrograph |
| COS | Corona Oxide Semiconductor |
| COSAC | Cometary Sampling And Composition |
| COSCAT | Coherent Scatter System |
| COSCI | Complete Open Shell Configuration Interaction |
| COSE | Committee On Optical Science And Engineering |
| COSEPUP | Committee On Science |
| COSHH | Control Of Substances Hazardous To Health (UK) |
| COSHI | Clearinghouse For Occupational Safety And Health Information |
| COSMIC | Computer Oriented Structure Models From Inadequate Derived Coupling Data |
| COSPAR | Committee On Space Research |
| COSS | Correlation Shift Scaling |
| COSTR | Collaborative Solar-Terrestrial Research |
| COSY | Correlation Spectroscopy |
| COTF | Classroom Of The Future |
| COV | Coefficient Of Variation |
| CP | Cellulose Propionate |
| CP | Chemical Pseudopotential |
| CP | Chemically Pure |
| CP | Coupled Pair (many-electron Theory) |
| CP-LSDA | Car-Parrinello Local Spin Density Functional |
| CP-TAPF | Cross-polarization Using Time-averaged Precession Frequency |
| CP/MAS | Cross Polarization/magic Angle Spinning [in Regard To NMR] |
| CPA | Chirped Pulse Amplification |
| CPA | Coherent Potential Approximation |
| CPA | Coupled-pair Approximation |
| CPAA | Charged Particle Activation Analysis |
| CPAC | Center For Process Analytical Chemistry |
| CPAP | Continuous Positive Airway Pressure |
| CPB | Cardiopulmonary Bypass |
| CPB | Coupled Pressure Bars |
| CPBA | Coulomb-projected Born Approximation |