| D | Danger area |
| Day |
| d | deci (0.1 = 10-1) |
| D & D | Design and development |
| Distress and diversion |
| d lat | Difference in latitude (nav) |
| d long | Difference in longitude (nav) |
| D/A | Digital-to-analogue |
| D/P | Documents against payment |
| DA | Decision altitude |
| Design authority |
| da | Draught aft |
| deca (10 = 101) |
| DAA | Defence Accounts Agency |
| DAB | Digital audio broadcast |
| DAC | Data acquisition and control |
| Digital-to-analogue converter |
| DAFS | Design-approved firms scheme |
| DAMA | Demand assignment multiple access (network) |
| DAP | Distributed array processor |
| DAR | Defense acquisition regulation |
| DARPA | Defense Advanced Research Projects Agency (USA) |
| DASCU | Digital automotive system control unit |
| DASS | Digital access signalling system |
| DAT | Digital audio tape |
| DB | Double bottom |
| dB | Decibel |
| DBIF | Data base interchange format |
| DBMS | Data base management system |
| DBS | Direct broadcast by satellite |
| Doppler beam sharpening (radar) |
| DC | Defence committee |
| dc | Direct current |
| DCA | Defence Codification Authority |
| Dual-capable aircraft |
| DCBA | Damage control breathing apparatus |
| DCC | Damage control centre |
| DCP | Display control panel |
| DCTN | Defence commercial telecommunications network |
| DCTS | Data communications terminal system |
| DD | Data dictionary |
| Draft for development (British Standard) |
| Dry dock |
| DDD | Direct-drive diesel |
| DDE | Direct data entry |
| DDI | Direct dialling-in |
| DDL | Data description language (computer) |
| DDM | Difference in depth modulation |
| DDT | Dichlorodiphenyltrichloroethane |
| Digital data transmission |
| DDVR | Displayed data video recorder |
| DE | Damage expectancy |
| Diesel-electric |
| DEAMS | Defence equipment acquisition and materiel support |
| DEC | Digital electronic control |
| Director, Equipment Capability |
| decl | Declination (nav) |
| DECS | Digital engine control system |
| DECT | Digital enhanced cordless telephone (standard) |
| DECU | Digital engine control unit |
| DED | Data element definition |
| Docking and essential defect (ship repair) |
| def | Defence |
| DEF STAN | Defence Standard (UK) |
| DEFRA | Department for Environment, Food and Rural Affairs |
| defrep | Defence readiness posture |
| deg | Degree |
| DEM | Digital elevation model |
| dep | Departure (nav) |
| DERA | Defence Evaluation and Research Agency (formerly) |
| DES | Data encryption standard |
| DESO | Defence Export Services Organisation (MoD) |
| dest | Destination |
| det | Detached/detachment |
| detonation |
| dev | Deviation (nav) |
| DEW | Defensive electronic warfare |
| DF | Defensive fire |
| Direction finding |
| DFDR | Digital flight data recorder |
| DFID | Department for International Development |
| DFR | Departure flow regulation |
| DFS | Data fusion system |
| Detailed functional specification |
| DFT | Department for Transport |
| Distance from touchdown |
| DFTI | Distance from touchdown indicator |
| DFTS | Defence fixed telecommunications system |
| DGC | Degaussing coil |
| DGI | Digital geographic information |
| DGITS | Director General Information Technology Systems |
| DGNSS | Differential global navigation satellite system |
| DGPS | Differential global positioning system |
| DGZ | Desired ground zero |
| DH | Decision height (aircraft) |
| Department of Health |
| DHE | Data handling equipment |
| DHFS | Defence Helicopter Flying School |
| DI | Development item |
| DIA | Defence Intelligence Agency |
| dia | Diameter |
| DIAS | Distributed information architecture for ships |
| DID | Data item description |
| DIFAR | Direction frequency analysis and recording |
| Direction-finding acoustic ranging |
| DIFET | Double injection field effect transistor |
| DIGEST | Digital geographic information exchange standard |
| DILCS | Dedicated intelligence loop circuit system |
| DIMM | Dual in-line memory module |
| DIMPS | Distributed message processing system |
| DIMS | Data and information management service (of GOOS) |
| Director, International Military Staff |
| DIPS | Diver information processing system |
| DISCO | Digital scan converter |
| dist | Distance |
| distaff | Directing staff |
| div | Division |
| dk | Deck |
| DL | Demarcation line |
| DLBPS | Developing land-based producer state |
| DLL | Dynamic link library |
| DLO | Defence Logistics Organisation (MoD) |
| DLP | Digital light projection |
| DMA | Defence Manufacturers Association |
| Direct memory access |
| DMC | Data module code |
| Display management computer |
| Dough-moulding compound |
| DME | Distance-measuring equipment |
| DMFC | Direct methanol fuel cell |
| DMG | Distance made good (nav) |
| DML | Data manipulation language |
| dml | Demolition |
| DMU | Data management unit |
| DNC | Digital nautical chart |
| DNS | Domain name system (internet) |
| DO | Diesel oil |
| Drawing office |
| DOB | Deployment operating base |
| doc | Document |
| DOF | Degrees of freedom (motion platform) |
| DOLCE | Digital data direct on-line cryptographic equipment |
| DOS | Denial of service |
| Digital operating system |
| Disk operating system |
| DOT | Department of Transport |
| DP | Data processing |
| Doppler pulse (radar) |
| DPA | Defence Procurement Agency (MoD) |
| DPC | Defence planning committee |
| DPM | Disruptive pattern material |
| DPP | Defence planning and policy |
| DPSN | Data packet switch network |
| DR | Dead reckoning (nav) |
| DRAM | Dynamic random access memory (computer) |
| DRAW | Direct read after write (data store) |
| DRC | Defence review committee |
| DRDF | Digital resolution direction finder |
| DRFAhd | Double-ring full ahead |
| DRFAstn | Double-ring full astern |
| DRG | Directional receiver group |
| drk | Derrick |
| DRM | Digital radio mondiale |
| DROPS | Demountable rack off-loading and pick-up system |
| DS | Decision sheet |
| Direct support |
| Directing staff |
| Dressing station |
| DSA | Defence shipping agency |
| Disposal Sales Agency |
| DSB | Double-side band (radio) |
| Dry support bridge |
| DSC | Defence Shipping Council |
| Direct selective calling (radio) |
| DSCS | Defence satellite communications system |
| DSEB | Defence Shipping Executive Board |
| DSL | Digital subscriber line |
| DSO | Digital storage oscilloscope |
| DSP | Digital signal processor |
| DSR | Distance-selling Regulation |
| DSS | Data selection sheet |
| Decision support system |
| DSSSL | Document style semantics and specification language |
| DSTL | Defence Science and Technology Laboratory |
| DSTV | Deep submerged television |
| DSU | Direct support (or supply) unit |
| DT | Deep tank |
| DTD | Document type definition |
| DTDM | Digitised time division multiplex (radio) |
| DTE | Data terminal equipment |
| DTED | Digital terrain elevation data |
| DTG | Date/time group |
| DTI | Department of Trade and Industry |
| DTL | Diode transistor logic |
| DTM | Digital terrain matrix |
| DTMF | Dual-tone multi-frequency (radio) |
| DTN | Defence teleprinter network |
| DTOP | Digital topographic data |
| DTP | Desktop publishing |
| DTR | Data transfer rate |
| DUC | Dual capable |
| DVAL | Demonstration and validation |
| DVD | Digital video disk |
| DVI | Direct voice input |
| DVM | Digital voltmeter |
| DVOR | Doppler VHF omni-directional ranging equipment |
| DVT | Digital voice terminal |
| DW | Dead weight |
| DWC | Dead weight capacity |
| DWCC | Dead weight cargo capacity |
| DWCT | Dead weight cargo tons |
| DWDM | Dense wave-division multiplex |
| DWL | Displacement on the water line |
| DWS | Defence Works Services |
| DWT | Dead weight tonnage |
| DZ | Dropping zone |
