ADP
- 401(k)
- AD Plastik
- ADP (company)
- Action Democratic Party (Nigeria)
- Acyclic dependencies principle
- Adap language
- Adenosine diphosphate
- Adrian Peterson
- Advanced Data Protection
- Aeropuertos del Perú
- Agua del Pueblo
- Air displacement plethysmography
- Alabama Democratic Party
- Alaska Democratic Party
- Alessandro Del Piero
- AllDay Project
- Alpha Delta Phi
- Alpha Delta Pi
- American Democracy Project (527 group in Florida)
- American Democracy Project (AASCU initiative)
- Amhara Democratic Party
- Ammonium dihydrogen phosphate
- Ampara Airport
- Andorran peseta
- Android Dev Phone
- Arab Democratic Party (Israel)
- Arab Democratic Party (Lebanon)
- Arizona Democratic Party
- Arkansas Democratic Party
- Association for the Development of Pakistan
- Association of Directory Publishers
- Assyrian Democratic Party (Syria)
- Attach Detection Protocol
- Azerbaijan Democratic Party
- Aéroports de Paris
- California Department of Alcohol and Drug Programs
- SLAF Anuradhapura