ADT
- ADT College
- ADT Inc.
- Abstract data type
- Abu Dhabi Terminals
- Active Denial Technology
- Ada Municipal Airport
- Adirondack Trailways
- Admission, discharge, and transfer system
- Adnyamathanha language
- Air Departure Tax
- Algebraic data type
- Alternating decision tree
- American Discovery Trail
- American death triangle
- Ana de Teresa
- Androgen deprivation therapy
- Android software development
- Arogenate dehydratase
- Asian Development Tour
- Asociación Deportiva Tarma
- Asynchronous data transfer
- Atlantic Daylight Time
- Automatic double tracking
- Average Daily Traffic
- Azadithiolate cofactor
- Azkals Development Team
- Comps (casino)
- Dvorak technique
- Harro Adt
- Katrin Adt