- Initialism of die-deterioration doubling (a common form of mint-made error on coins that results from degradation of the die used to strike the coin)
- (music) A designation on prerecorded compact discs indicating a "full digital recording" (recorded, mixed and mastered in digital).
- (organic chemistry) Initialism of dichlorodiphenyldichloroethane (insecticide related to DDT)
- (software design) Initialism of domain-driven design (methodology and set of priorities for object oriented programming)
- (telecommunications) Initialism of direct distance dialing (network-provided service that enables non-local telephone calls to be made without operator assistance)