| Abbreviation | Definition |
|---|---|
| DEAT | Department of Environmental Affairs and Tourism |
| DEC | Department of Environmental Conservation |
| DEC | Department of Environmental Control |
| DEC | Disaster Emergency Committee |
| DEC | District Emergency Coordinator |
| DED | Department of Economic Development |
| DEDO | Delaware Economic Development Office |
| DEED | Department of Education and Early Development |
| DEED | Department of Employment and Economic Development |
| DEFAC | Delaware Economic and Financial Advisory Council |
| DELA | Delaware |
| DEM | Department of Environmental Management |
| DEP | Department of Environmental Protection |
| Dept. | Department |
| DER | Disaster and Emergency Response |
| DERA | Department of Educational Research Assessment |
| DERB | City of Derby |
| DERC | Delhi Electricity Board Regulatory Commission |
| DERM | Department of Environmental Resources Management |
| DERP | Denver Employees Retirement Plan |