| Acronym | Definition |
|---|
| ATI | Array Technology Inc. (manufacturer of hardware/software products) |
| ATI | Advanced Technology Institute |
| ATI | Advanced Training Institute (International homeschool group) |
| ATI | Access to Information |
| ATI | Agricultural Training Institute (Philippines) |
| ATI | Advanced Training Institute (India) |
| ATI | Assistance Technique d'Ingénieur (French: Technical Support Engineer) |
| ATI | Alternatives to Incarceration |
| ATI | Aviation Training Institute |
| ATI | Applied Technology Institute |
| ATI | Accessible Technologies Inc. (supercharger manufacturer) |
| ATI | Air Transport Industry |
| ATI | Anti-Trust Immunity (air travel) |
| ATI | Appropriate Technology International (Washington, DC) |
| ATI | Aptitude-Treatment Interaction (behavioral science) |
| ATI | Amplifier Technologies Inc. |
| ATI | Above the Influence (government anti-drug campaign) |
| ATI | Above-Threshold Ionization |
| ATI | Adjusted Taxable Income |
| ATI | Along-Track Interferometry |
| ATI | Accelerated Technology, Inc |
| ATI | American Trades Institute |
| ATI | Advanced Technologies Incorporated |
| ATI | Any Time Interrogation |
| ATI | Average Total Inspection |
| ATI | American Tasting Institute |
| ATI | Advanced Telecommunications Institute |
| ATI | Alternativa de Transporte Integrado (Integrated Alternative Transportation, San Juan) |
| ATI | Automatic Transaction Initiation |
| ATI | Audio-Tactile Interface (US Election Assistance Commission) |
| ATI | Automatic Test Inhibit |
| ATI | Associate of the Textile Institute |
| ATI | Artillery Target Intelligence |
| ATI | Automated Technical Information |
| ATI | Air Transport Indicator |
| ATI | American Transtech Inc. (carrier for AT&T T1 circuits) |
| ATI | Associated Technologies, Inc. |
| ATI | Anaesthetists in Training in Ireland |
| ATI | Associacion de Tecnicos de Informatica (Spain) |
| ATI | Any Three Initials (band) |
| ATI | American Training International (California) |
| ATI | Activist's Times Incorporated |
| ATI | Automatic Track Initiation |
| ATI | Air Technical Index |
| ATI | Albuquerque Technology Incubator |
| ATI | Aquamira Technologies, Inc. |
| ATI | Air Toxics Index |
| ATI | Anjuman Talaba Islam (aka Anjuman Talaba-e-Islam; Sunni group; Pakistan) |
| ATI | Approved Training Institution |
| ATI | Automation of Technical Information |
| ATI | Andromeda Training, Inc. |
| ATI | AudioTechnologies Inc |
| ATI | American Trainco, Inc (Centennial, CO) |
| ATI | Automated Tactical Intelligence |
| ATI | Airborne Tracker-Illuminator |
| ATI | Application Template Interface |
| ATI | AWSIM to TBMCS Interface |
| ATI | Aware Technology International (UK) |
| ATI | Arithmétique et Théorie de l'Information (French: Arithmetic and Information Theory) |
| ATI | Alternative Technologies International (Muncy, PA) |
| ATI | Arizona Toxics Information Inc. (Bisbee, AZ) |
| ATI | Achievement Through Innovation (ATI Systems) |
| ATI | Atmospheric Technologies Inc. (Calgary, AB, Canada) |
| ATI | Available Taxable Income (student financial aid) |
| ATI | Agence du Traitement de l'Information |
| ATI | Accurate Technologies Incorporated (Wixom, MI) |
| ATI | Automotive Training Institutes |
| ATI | Ambient Temperature Illuminator (military device; US DoD) |
| ATI | Acronis True Image (disk imaging software) |
| ATI | All Taxes Included (sales) |
| ATI | Allegiance Telecom, Inc. (Dallas, TX) |
| ATI | Air Techniques, Inc. (air emission control industry; Marietta, GA) |