APD
- APD-40
- Acid peptic diseases
- Afferent pupillary defect
- Air Passenger Duty
- Airport Police Division
- Akron Police Department
- Albany Port Railroad
- Albuquerque Police Department
- Alliance for Democracy (Dominican Republic)
- Alpha Phi Delta
- American political development
- Amtrak Police Department
- Anchorage Police Department
- Annapolis Police Department
- Antimicrobial Peptide Database
- Antioch Police Department
- Antipsychotic drug
- Antisocial personality disorder
- Apopka Police Department
- Apple Accessory Products Division
- Appledore (Kent) railway station
- Arcadia Police Department
- Atlanta Police Department
- Auditory processing disorder
- Aurora Police Department
- Austin Police Department
- Autoimmune progesterone dermatitis
- Avalanche photodiode
- Avoidant personality disorder
- High-speed transport
- Pamidronic acid
- Peace Through Law Association
- Sudanese Arabic