| Academic Cooperation Assocation | Academic & Science |
| Atacama Compact Array | Academic & Science |
| American Chichlid Association | Academic & Science |
| Atlanta College of Art | Academic & Science |
| Awassa College of Agriculture | Academic & Science |
| Aerospace Consultancy Associates | Academic & Science |
| Actual Cost Adjustment | Accounts and Finance |
| Associate of The Institute of Chartered Accountants In England and Wales | Accounts and Finance |
| Associate of The Institute of Chartered Accountants In Ireland | Accounts and Finance |
| Accreditation Council for Accountancy | Accounts and Finance |
| Acapulco | Airport Code |
| Awfully Clever Accountant | Business |
| Allstates Certificate Advantage | Business |
| A Chartered Accountant | Business |
| American Chiropractic Association | Business |
| Anti Copyright Association | Business |
| Asean Cosmetic Association | Business |
| Annual Career Authorization | Business |
| Apples of California Agriculture | Business |
| A Cut Above | Business |
| Adobe Certified Associate | Business |
| Amoskeag Company A | Business |
| All Correspondence Answered | Business |
| American Cable Association | Community |
| Amazon Conservation Association | Community |
| Angel Capital Association | Community |
| Afro Caribbean Association | Community |
| Arms Control Association | Community |
| American Crystallographic Association | Community |
| American Counseling Association | Community |
| American Communication Association | Community |
| Academy of Certified Archivists | Community |
| American Cryptogram Association | Community |
| American Canyoneering Academy | Community |
| American Canyoneering Association | Community |
| Association of Canadian Advertisers | Community |
| Australian Clan Alliance | Community |
| Animated Cel Archive | Community |
| Association of Canadian Archivists | Community |
| American Camp Association | Community |
| Amputee Coalition of America | Community |
| Asia Children's Assistance, LTD. | Community |
| American Cornhole Association | Community |
| Atlantic Center for the Arts | Community |
| Accredited Certifiers Association | Community |
| Annual Catholic Appeal | Community |
| Autodesk Community AutoCAD | Community |
| American Compliance Association | Community |
| Association of Chinese Americans | Community |
| Alabama Christian Academy | Community |
| Adult Children of Alcoholics | Community |
| Alley Cat Allies | Community |
| Animal Charities of America | Community |
| Adult Children Anonymous | Community |
| American Camping Association | Community |
| Alberta College of Art (part of SAIT and prior to 1960 part of PITA) | Community |
| American Correctional Association | Community |
| American Coatings Association | Community |
| Appalachian College Association | Community |
| Avid Customer Association | Community |
| Adaptive Channel Allocation | Computer and Networking |
| Aspect Camera Assembly | Computing |
| Agent Character | Computing |
| Audio Compression Algorithm | Computing |
| Adaptive Component Architecture | Computing |
| Adaptive Computing Architecture | Computing |
| Auto Contingent Allegiance | Computing |
| Asynchronous Communication Adapter | Computing |
| Audio Content Architecture | Computing |
| Adjacent Channel Attenuation | Computing |
| Apple Certification Alliance | Computing |
| Automatic Component Activation | Computing |
| Access Control Agent | Computing |
| Application Center Administration | Computing |
| Applications of Computer Algebra | Computing |
| Avanade Connected Architectures | Computing |
| Arrowpoint Content Awareness | Computing |
| ACA Token | Cryptocurrency |
| American College of Apothecaries | Educational Institute |
| Anisotropically Conductive Adhesive | Electronics |
| Project Manager Workbench Project File | File Type |
| Association Canadienne des Automobilistes | General |
| Agence Conseil Automobile | General |
| Agence Coloniale Automobile | General |
| Antigomobilismo Circuito Das Aguas Paulista | General |
| Automobile Club Ardennais | General |
| Automobiles de la Cote d'Azur | General |
| Alpine Club Alsace | General |
| Automotive Corporation of America | General |
| Agence Commerciale Automobile | General |
| Automotive Consumer Advocates | General |
| Auto Care Association | General |
| Australian Corvettes Association | General |
| American Corvette Association | General |
| Associazione Collaudatori di Automobili | General |
| American Camaro Association | General |
| American Car Audio | General |
| Alpine Cote d'Azur | General |
| Autobody Craftsman Association | General |
| Automobil Club d'Andorra | General |
| Auto Crime Association | General |
| Antique and Classics Automobile | General |
| Auto Club Altena | General |
| Attache Commercial Automobile | General |
| Automovil Club de Almeria | General |
| Automovil Club Alicante | General |
| Automotive Career Academy | General |
| Auto Consumer Alliance | General |
| Automotive Composites Alliance | General |
| Active Cornering Assist | General |
| Amateurs de Citroen Anciennes | General |
| Automobile Club d'Aix | General |
| Automobile Club d'Alsace | General |
| Automobile Club d'Auvergne | General |
| Association Canadienne de l'Autobus | General |
| American Citizens Abroad | General |
| American Country Awards | General |
| Agricultural Crop Additive | General |
| American Control Administration | General |
| Apollo Centaurus and Atlasdreef | General |
| Another Confusing Acronym | General |
| Australian Cloggers Association | General |
| Adaptive Cruise Assistant | General |
| Always Cancelled Airplanes | General |
| Automovil Club Argentino | General |
| Automobile Club Albania | General |
| American Canine Association | General |
| Automobile Club Association | General |
| Advanced Collision Avoidance | General |
| Atelier de Construction Automobile | General |
| Anchorage Corvette Association | General |
| Abarth Club America | General |
| Asian Communication Awards | General |
| Almost a Chartered Accountant | General |
| Automobile Club of America | General |
| Acrolein Cyanohdryinacetate An | General |
| Accela Citizens Access | General |
| Abbreviations com American | General |
| Alliance of Criminal Activities | Governmental |
| Advance Cargo Advice | Governmental |
| Automotive Club Alliance | Governmental |
| Accreded Certifying Agent | Governmental |
| Assistant Circuit Attorney | Governmental |
| Anti-Corruption Agency | Governmental |
| Agency for Cultural Affairs | Governmental |
| Arizona Commerce Authority | Governmental |
| Assembly Constitutional Amendment | Governmental |
| Arkansas Code Annotated | Governmental |
| Air Commerce Act | Governmental |
| Army Contracting Agency | Governmental |
| Allied Control Authority | Governmental |
| Affordable Care Act | Healthcare |
| Asociación Casa Alianza | International |
| Asociación Cristiana Academia | International |
| Associate Chartered Accountant | Jobs |
| Arithmetic Comprehension Axiom | Maths |
| Adaptive Conjoint Analysis | Maths |
| Anterior commissure (commissura anterior-pars anterior)[Brain] | Medical |
| acetoacetate | Medical |
| Acquired Child Aphasia | Medical |
| Acrodermatitis Chronica Atrophicans | Medical |
| Acute Cerebellar Ataxia | Medical |
| Acute Cutaneous Anaphylaxis | Medical |
| adenylyl cyclase A | Medical |
| Adrenal Cortex Autoantibodies | Medical |
| aminocaproic acid | Medical |
| Anterior Cerebral Artery | Medical |
| Anterior Communicating Artery | Medical |
| Anhydrous Codeine Alkaloid | Medical |
| Anti-Cardiolipin Antibody | Medical |
| Anti-Centromere Antibody | Medical |
| Area Cost Adjustment | Medical |
| Advanced Cargo Aircraft | Military and Defence |
| Airborne Collection Assembly | Military and Defence |
| Automatic Conference Arranger | Military and Defence |
| Airlift Clearance Authorities | Military and Defence |
| Airspace Control Authority | Military and Defence |
| Airspace Coordination Area | Military and Defence |
| Air Combat Command | Military and Defence |
| After Contract Award | Military and Defence |
| Automatic Channel Assignment | Military and Defence |
| Andres Castro Arms | Military and Defence |
| Army Control Authority | Military and Defence |
| Airlift Clearance Authority | Military and Defence |
| Address Control Application | Networking |
| Africa Capacity Alliance | Regional |
| Acapulco, Mexico | Regional |
| America, Canada, and Australia | Regional |
| Australian Cricketers Association | Regional |
| Arithmetical Comprehension Axiom | Softwares |
| American Canoe Association | Sports |
| Adventure Cycling Association | Sports |
| Austin Cycling Association | Sports |
| Academics Community and Athletics | Sports |
| Automatic Circuit Assurance | Telecommunication |
