| Abbreviation | Definition |
|---|---|
| DEC | Digital Equipment Corporation |
| DECCO | DEfense Commercial Communications Office |
| DECL | DECLassify |
| DECM | Defensive Electronic Countermeasures |
| DECS | Daily Expenditure of Combat Supplies |
| DED | Data Element Dictionary |
| DED | Data Entry Display |
| DED | Dynamic Entity Database |
| DEE | Dental Emergency Encounter |
| DEERS | Defense Eligibility Enrollment System |
| DEERS | Defense Enrollment Eligibility Reporting System |
| DEET | Directed Energy EOD Tool |
| DEEVAL | Detailed Europe Evaluation |
| DEF | Defense |
| DEF | Defensive |
| DEF | Defusing |
| DEF | Development and Evaluation Facility |
| DEFAC | Dining Facility |
| DEFCON | Defense Readiness Condition |
| DEFI | Data Entry File Inquiry |