| Acronym | Definition |
|---|
| ACT | Activity |
| ACT | Active |
| ACT | Actual |
| ACT | American College Test |
| ACT | Active (Telabs) |
| ACT | Actual (Sprint) |
| ACT | Actor |
| ACT | Activation |
| ACT | Ancestors |
| ACT | Australian Capital Territory (Australian state/territory) |
| ACT | Assertive Community Treatment |
| ACT | Arms Control Today (magazine) |
| ACT | American College Testing |
| ACT | Action by Churches Together |
| ACT | Association for Competitive Technology |
| ACT | America Coming Together |
| ACT | American Conservatory Theater (Repertory Theatre Company In San Francisco, CA) |
| ACT | Application Compatibility Toolkit |
| ACT | Association of Corporate Treasurers |
| ACT | Accounting Division |
| ACT | Association of Commercial Television in Europe (Brussels, Belgium) |
| ACT | About Clinical Trials |
| ACT | Acceptance and Commitment Therapy (clinical psychology) |
| ACT | Artemisinin-Based Combination Therapy |
| ACT | Allied Command Transformation |
| ACT | American Council for Technology |
| ACT | Activated Clotting Time |
| ACT | Advanced Computer Technology |
| ACT | Advance Corporation Tax |
| ACT | Action Tracking |
| ACT | Advanced Concept Technology |
| ACT | Action for Children's Television |
| ACT | Active Control Technology |
| ACT | Advanced Clutch Technology (automobile) |
| ACT | Advanced Cell Technology Inc. (cloning research company) |
| ACT | Anti-Car Theft |
| ACT | Amazon Conservation Team |
| ACT | A Contemporary Theatre (Seattle, WA, USA) |
| ACT | Association for Commuter Transportation |
| ACT | Automated Confirmation Transaction Service (NASD) |
| ACT | Arts & Culture Trust (South Africa) |
| ACT | Association for Children's Palliative Care (Bristol, UK) |
| ACT | Advanced Communication Technology |
| ACT | Air Cargo Terminal |
| ACT | Association of Civilian Technicians |
| ACT | Alliance for Cannabis Therapeutics |
| ACT | Alliance for Coastal Technologies (NOAA funded partnership) |
| ACT | Accurate Complete Timely |
| ACT | Acoustical Ceiling Tile |
| ACT | Advanced Concepts Team (European Space Agency) |
| ACT | Advanced Corporation Tax |
| ACT | Advanced Concepts and Technology (US Army) |
| ACT | Adaptive Computing Technology |
| ACT | Average Cycle Time |
| ACT | Alliance of Concerned Teachers (Philippines) |
| ACT | Agents Council for Technology Act (insurance; ecommerce) |
| ACT | Apologetics Coordination Team |
| ACT | Alliance for Children and Television (Canada) |
| ACT | Association of Consumers and Taxpayers (New Zealand political party) |
| ACT | Adaptive Control of Thought |
| ACT | Artist Trading Card |
| ACT | All Children Together (Northern Ireland) |
| ACT | Automatic Custody Transfer |
| ACT | Association for Citizenship Teaching (UK) |
| ACT | Air Charge Temperature (automotive sensor) |
| ACT | American College of Theriogenologists |
| ACT | Air Combat Tactics |
| ACT | Aircrew Coordination Training |
| ACT | Attitude Control Thrusters |
| ACT | Access Control Table |
| ACT | Alternative Control Technology |
| ACT | Acyl-CoA Thioester Hydrolase |
| ACT | Association of Christian Therapists |
| ACT | Association of Classroom Teachers |
| ACT | Arbre À Cames En Tête (French: overhead camshaft) |
| ACT | Aid for College Tuition |
| ACT | Active Citizenship Today (Constitutional Rights Foundation) |
| ACT | Autoridad de Carreteras y Transportación (Spanish) |
| ACT | Activator of CREM in Testis |
| ACT | Advanced Corporate Tax |
| ACT | Acoustic Charge Transport |
| ACT | Advanced Composites Technology |
| ACT | Alliance for Converging Technologies (now called Digital 4Sight) |
| ACT | Advanced Coating Technology (for chemical resistant labels) |
| ACT | Agenda for Children Tomorrow (New York City program) |
| ACT | Aden Container Terminal |
| ACT | Abuse Counseling and Treatment, Inc. |
| ACT | Applied Creative Technologies |
| ACT | Activated Complex Theory |
| ACT | Annual Change Traffic |
| ACT | Advance Corporate Tax |
| ACT | Asociación de Clubes de Traineras (Spanish: Boat-Racing Clubs Association) |
| ACT | Actual Cycle Time |
| ACT | Alabama–Coosa–Tallapoosa River Basin Compact |
| ACT | Activity Bit |
| ACT | Alachua Conservation Trust (Florida, USA) |
| ACT | Axial Computed Tomography |
| ACT | Atmospheric Chemical-Transport |
| ACT | Advanced Configuration Tool |
| ACT | Waco, TX, USA - Madison Cooper (Airport Code) |
| ACT | Alliance for Community Transformation (Lagos, Nigeria) |
| ACT | African Conservation Trust |
| ACT | Air Control Team |
| ACT | Alternating Current Transformer |
| ACT | Approach Control Tower (aviation) |
| ACT | Architecture Characterization Template |
| ACT | Apollo Civic Theatre |
| ACT | Advance Computer Technology (Program) |
| ACT | American Cell Technology |
| ACT | Access Control Technologies, Inc. |
| ACT | Alternate Cover Test (ophthalmology) |
| ACT | Amarillo City Transit |
| ACT | Advanced Concepts and Technologies International, LLC |
| ACT | Action for Conservation through Tourism (UK) |
| ACT | Applied Computerized Telephony (HP) |
| ACT | Associated Conservatives of Texas |
| ACT | Alliance for Competitive Telecommunications |
| ACT | Analysis Control Team |
| ACT | Application Center for Technology |
| ACT | Asociación de Cooperación Tecnica (Technical Cooperation Association, Guatemala) |
| ACT | Activity Coordination Team |
| ACT | Additional Centre Tank |
| ACT | Atmospheric Corrosion Testing |
| ACT | Aromatherapy Conference Tours |
| ACT | Acquisition Coordination Team |
| ACT | Actual Cost of Testing |
| ACT | Active Control Technique |
| ACT | African-American Collective Theater (Washington, DC) |
| ACT | Americans for Competitive Telecommunications |
| ACT | Advantage Coaching and Training |
| ACT | American Combat Teams |
| ACT | Advertising Club of Toronto |
| ACT | Advance Corporate Training Ltd. |
| ACT | Algebraic Compiler and Translator |
| ACT | Action Collaboration Team |
| ACT | Advocacy, Communications, and Training |
| ACT | Advanced Component Technologies, Inc. |
| ACT | Asynchronous Control Transfer |
| ACT | Advanced CMOS, TTL Compatible (integrated circuit type description) |
| ACT | Actual Control Technology |
| ACT | Accounting, Consulting & Training |
| ACT | American Corporations for Thailand |
| ACT | Academy of the Company Theatre (Norwell, MA) |
| ACT | Account Control Table |
| ACT | AIDS Counseling and Training |
| ACT | Analysis Compliance & Training |
| ACT | Absolute Congestion Threshold (Newbridge) |
| ACT | Administrative Council Team |
| ACT | Analysis of Complexity Tool |
| ACT | Air Contract Transportation Tag (US postal service) |
| ACT | Advanced Concepts Test |
| ACT | Aluminum Clay Tool (well logging) |
| ACT | Advanced Cordless Technologies (Europe) |
| ACT | Agape Copeland Train (South Africa) |
| ACT | Aircrew Combative Training (AirCare International Ltd.) |
| ACT | Arctic Cat Technology |
| ACT | Airborne Communications Terminal |
| ACT | Arkansas CAMA Technology, Inc (Hot Springs, AR) |
| ACT | Automatic Cobb Tester (water uptake tester) |
| ACT | Augmented Catalytic Thruster |
| ACT | Anagram and Copy Treatment (speech-language pathology) |
| ACT | Altitude Compensated Tilt |
| ACT | Association of Cleaning Technicians (NJ, NY, PA, CT, MD, VA) |
| ACT | Advanced Capability Tanker |
| ACT | Assisted Communication Transactions |
| ACT | Automatic Call Tracking (Sprint) |
| ACT | Activities, Contacts, Time (Symantec contact manager software) |
| ACT | Advanced Computer Techniques, Inc |
| ACT | Automatic Code Translator |
| ACT | Advanced Communications Transceiver |
| ACT | Active Charge Transport |
| ACT | Acquisition Coordinating Team |
| ACT | Advanced Customer Testing |
| ACT | Advanced Cargo Transport |
| ACT | Advanced Core Test |
| ACT | Armored Cavalry Trainer |
| ACT | Analyst Control Terminal |
| ACT | Adaptive Client Technology (Rockwell) |
| ACT | Attack Cycle Timeline (timed events required to attack a target) |
| ACT | Airborne Communications Technician |
| ACT | Automated Coordinate Transfer |
| ACT | Apache Crew Trainer |
| ACT | Automated Control of Trainees |
| ACT | Account Contact Tool |
| ACT | Advanced Channelized Transmission |
| ACT | Access Charge Terminal |
| ACT | Advanced Countermeasure(s) Technique(s) |
| ACT | Advanced Carbide Test |
| ACT | Analog Cordless Telecommunications |
| ACT | Application Centric Terminal (IBM) |
| ACT | Analytical Coordinated Team |
| ACT | Accumulated Cell Time |
| ACT | Alliance for Conflict and Transformation (Alexandria, Virginia) |
| ACT | Aqueous Catch Tank |
| ACT | Allentown College Theater |
| ACT | Air Correlation Tracker |
| ACT | Automatic Calibration using Transmitting signals |
| ACT | Analytical Cold Trap |
| ACT | Alabama Contemporary Theater |
| ACT | Arte, Color Y Texto (Spanish: Art, Color and Text; Guatemala) |