| Acronym | Meaning |
| ECQB | Electrochemical Quartz Crystal Balance |
| ECR | Eriochrome Cyanine Rpar |
| ECR | Electron Cyclotron Resonance |
| ECRA | Economic Cleanup Responsibility Act |
| ECRC | Environmental And Contaminants Research Center |
| ECRH | Electron Cyclotron Resonance Heating |
| ECRIS | Electron Cyclotron Resonance Ion Source |
| ECRR | Energy-corrected Rigid-rotor Approximation |
| ECS | Electro-Chemical Society |
| ECS | Electroconvulsive Shock |
| ECS | Energy-corrected Sudden (scaling Theory In Mol. Collisions) |
| ECS-EP | Energy-corrected Sudden-exponential Polynomial (scaling Law) |
| ECS-P | Energy-corrected Sudden-polynomial (scaling Law) |
| ECSC | European Coal And Steel Community |
| ECSFM | Electrochemical Scanning Force Microscopy |
| ECSPM | Electrochemical Scanning Probe Microscopy |
| ECSTM | Electrochemical Scanning Tunneling Microscopy |
| ECSXRF | Electrochemisorption X-ray Fluorescence |
| ECT | Emission-Computed Tomography |
| ECT | Ergodic Collision Theory |
| ECTDMS | Electrochemical Thermal Desorption Mass Spectroscopy |
| ECTFP | Empty-core Thomas-Fermi Pseudopotential |
| ECTR | Extended Connection Table Representation |
| ECU | Electronic Control Unit |
| ECVAM | European Center For The Validation Of Alternative Methods |
| ECWR | Electron Cyclotron Wave Resonance |
| ED | Effective Dose |
| ED | Electron Diffraction |
| EDA | Emergency Declaration Area |
| EDA | European Desalination Association |
| EDA | Electron Donor-acceptor |
| EDA | Ethylene Diamine |
| EDAX | Energy Dispersive Analysis Of X-rays |
| EDB | Ethylene Dibromide |
| EDC | Electron Energy Distribution Curve |
| EDC | Endocrine Disrupting Chemical |
| EDC | Ethylene Dichloride |
| EDCF | Endothelium-derived Contracting Factor |
| EDCS | Energy Distribution Curve Spectroscopy |
| EDD | Enforcement Decision Document |
| EDEC | Equal Distances Equal Charges Model |
| EDF | Electricite De France |
| EDF | Environmental Defense Fund |
| EDF | Energy Density Functional (theory In Electronic-property Calcn.) |
| EDFA | Er-doped Fiber Amplifier |
| EDGAR | Electronic Data Gathering |
| EDGAR | Emissions Database For Global Atm. Research |
| EDGE | Enhanced Data For GSM Evolution |
| EDHF | Endothelium-derived Hyperpolarizing Factor |
| EDL | Electric Double Layer |