| Abbreviation | Definition |
|---|---|
| DEGS | Duke Energy Generation Services |
| DEI | Dale Earnhardt Incorporated |
| DEI | Dale Earnhart Inc |
| DEI | Design Engineering Inc |
| DEI | Device Engineering Inc |
| DEI | Digital Electronic Imaging Systems, Inc. |
| DEI | Directed Electronic Inc |
| DEI | Directed Electronics, Inc. |
| DEI | Douglas Emmett Inc |
| DEI | Dynamic Engineering Inc |
| DEKA | Dean Kamen (of DEKA Research and Development Corporation, Manchester, NH, USA) |
| DEL | Dolphin Energy, Ltd. |
| DELCO | Dayton ELectric COmpany |
| DELCO | Dayton Engineering Laboratories Company in Ohio |
| DEMB | Douwe Egberts Master Blenders (D.E. Master Blenders) - coffee\food company |
| DEMG | Deltex Medical Group PLC |
| DEMI | Down East Microwave Inc |
| DEMI | Down East Microwave Inc. |
| DEP | Duurzame Energieproductie Pluimveehouderii |
| DEPCO | Dependable Education Products Company |