| ACA | Affordable Care Act✓ Verified | Medical |
| ACA | Argentine Cricket Association✓ Verified | Association, Organization, Sports, Cricket |
| ACA | Austrian Cricket Association✓ Verified | Association, Organization, Sports, Cricket |
| ACB | Afghanistan Cricket Board✓ Verified | Association, Organization, Sports, Cricket |
| ACE | Angiotensin-Cconverting Enzyme✓ Verified | Medical, Science, Biology, Chemistry, Chemical Compound |
| ACE | ASCII Compatible Encoding✓ Verified | Language, Computer Programming, Internet, Domain Name, Technology |
| ACH | Advanced Combat Helmet✓ Verified | Military, Air Force, Army, Defence, Special Forces, Hardware, Safety |
| ACWP&A | Assistant Controller of Warship Production and Acquisition✓ Verified | Military, Defence, Marine Corps, Navy, Weapon, Designation / Rank |
| Ad | Advertisement✓ Verified | Advertising, Business |
| AD | Anno Domini✓ Verified | Time |
| ADA | Aeronautical Development Agency✓ Verified | Military, Air Force, Defence, Weapon, Manufacturing, Research Center, Transport, Air Transport |
| ADC | Aide-de-camp✓ Verified | Military, Designation / Rank |
| ADC | Autonomous District Council✓ Verified | Government, Civic Administration, Organization |
| ADEA | American Dental Education Association✓ Verified | Education, Medical, Organization |
| ADIA | Abu Dhabi Investment Authority✓ Verified | Wealth Fund |
| ADIZ | Air Defense Identification Zone✓ Verified | Country, Border, Military, Air Force, Defence, Territory, Transport, Air Transport, Aircraft |
| ADM | Area Denial Munition✓ Verified | Military, Weapon |
| ADP | Anti-Naxalite Deployment✓ Verified | Military, Army, Defence |
| ADR | Association for Democratic Reforms✓ Verified | Election, Democracy, Organization, Politics |
| ADS | Airbus Defence and Space✓ Verified | Company, Military, Defence, Manufacturing |
| ADSTL | Adani Defence Systems and Technologies Limited✓ Verified | Company, Military, Defence, Weapon, Industry, Manufacturing |
| ADTCR | Air Defence Tactical Control Radar✓ Verified | Military, Defence, Satellite Technology |
| AEBS | Automatic Emergency Braking System✓ Verified | Software, System, Technology, Transport |
| AEN/MC | Assistant Engineer/Machines✓ Verified | Designation / Rank, Engineering, Railways |
| Aero | Top level domain for Aviation Industry✓ Verified | Internet, Domain Name, TLD |
| AFC | American Football Conference✓ Verified | Event, Sports, Football |
| AFL | American Football League✓ Verified | Event, Sports, Football |
| AFSh | Adsense for Shopping✓ Verified | Advertising, Business, Internet, Marketing, Software |
| AFSPA | Armed Forces Special Powers Act✓ Verified | Military, Legal, Policy |
| AFT | Armed Forces Tribunal✓ Verified | Military, Army, Legal |
| AGL | Above Ground Level✓ Verified | Aviation, Measurement Unit, Distance, Territory |
| AGM | Annual General Meeting✓ Verified | Business, Event, Finance, Meetings and Conferences |
| AGR | Adjusted Gross Revenue✓ Verified | Finance |
| AGRASR | Action Groups Aimed at Social Reconstruction✓ Verified | Government, Group, Scheme |
| AGTF | Anti-Gangster Task Force✓ Verified | Government, Civic Administration, Military, Army, Defence, Police, Law Enforcement |
| AIDS | Acquired Immune Deficiency Syndrome✓ Verified | Medical, Disease |
| AIDSO | All India Democratic Students Organisation✓ Verified | Organization |
| AIF | Alternative Investment Fund✓ Verified | Finance, Fund, Investment |
| AINRC | All India N R Congress✓ Verified | Political Party |
| AIO | All in One✓ Verified | Technology |
| aka | also known as✓ Verified | Slang |
| AM | Ante Meridiem✓ Verified | Time |
| AMC | Annual Maintenance Charges✓ Verified | Business, Finance, Legal |
| AMC | Annual Maintenance Contract✓ Verified | Business, Document, Legal |
| AMC | Asset Management Company✓ Verified | Business, Company, Finance |
| AMS | Apollo Micro Systems Limited✓ Verified | Business, Company, Military, Defence, Manufacturing |
| AMUL | Anand Milk Union Limited✓ Verified | Company, Food |
| ANC | Andaman & Nicobar Command✓ Verified | Military, Navy, Facility |
| AOB | Andhra-Odisha Border✓ Verified | Border, State, Geography |
| AOF | Append-Only File✓ Verified | File Extension, Technology |