| Acronym | Definition |
|---|
| ATU | Arkansas Tech University |
| ATU | Amalgamated Transit Union |
| ATU | ACORN (Association of Community Organizations for Reform Now) Tenants Union |
| ATU | African Telecommunications Union |
| ATU | Actuant Corporation (stock symbol) |
| ATU | Across the Universe (Beatles song and 2007 movie) |
| ATU | Autorisation Temporaire d'Utilisation (French: Temporary Use Authorization; pharmacology) |
| ATU | Antenna Tuning Unit |
| ATU | ADSL Transceiver Unit (ITU-T) |
| ATU | Aerobic Treatment Unit |
| Atu | Agrobacterium Tumefaciens |
| ATU | ADSL Terminal Unit |
| ATU | Address Translation Unit |
| ATU | Abstract Tribe Unique (hip hop) |
| ATU | Alcohol Tax Unit |
| ATU | Anchorage Telephone Utility |
| ATU | AIDS Treatment Update |
| ATU | Advanced Training Unit (US Navy) |
| ATU | Audio Terminal Unit |
| ATU | Automatic Tuning Unit |
| ATU | Antiterrorist Unit |
| ATU | Awareness, Trial and Usage |
| ATU | Acute Treatment Unit |
| ATU | Asian Taekwondo Union |
| ATU | account team unit (UK) |
| ATU | Approaching the Unreal (Rock Band players' group; Australia) |
| ATU | Appalachian Terror Unit (band) |
| ATU | Air Terminal Unit (HVAC) |
| ATU | Accumulated Thermal Unit |
| ATU | Auto Trac Universal (John Deere assisted steering system) |
| ATU | Actions Transports Urgents (French: Urgent Action Transport) |
| ATU | Administrative Target Unit |
| ATU | Automatic Tray Unsleever (US postal Service) |
| ATU | All Terrain Unicycle |
| ATU | Agency Terminal Unit |
| ATU | Automatic Top-Up (Virgin Mobile USA) |
| ATU | Alarm Transfer Unit |
| ATU | American Tippler Union |
| ATU | Analog Test Unit |
| ATU | Auxiliary Test Unit |
| ATU | Analog Trip Unit |
| ATU | Amplifier Test/Technology Unit |
| ATU | Automated Tracking Unit |
| ATU | Automatic Testing Unit |
| ATU | Automated Timing Unit |
| ATU | Audio Tape Unit |
| ATU | AUTODIN Transfer Unit |
| ATU | Army Test Unit |
| ATU | Arizona Treasures Unlimited, Inc. (Phoenix, AZ) |
| ATU | Application Terminal Unit |
| ATU | Automated Translation Unit |
| ATU | All Things Ukrainian, Inc (North Carolina importer) |
| ATU | Auto Teile Unger (German auto parts company) |
| ATU | Aquatic Therapy University (Plymouth, MN) |
| ATU | Amphibious Task Unit (joint military training project; Finland and Sweden) |