| Acronym | Definition |
|---|
| Au | Gold |
| AU | African Union (formerly Organization of African Unity) |
| AU | Air University (US Air Force) |
| AU | Australia (top-level domain name) |
| AU | Audio (file name extension) |
| AU | Author |
| AU | Audio Unit |
| AU | American University (Washington, DC, USA) |
| AU | Assessment Unit |
| AU | Austria |
| AU | Adelaide University (University of Adelaide, Australia) |
| AU | Anderson University (Indiana) |
| AU | Assumption University |
| AU | Alfred University |
| AU | Automatic (welding) |
| AU | Americans United (for the Separation of Church and State: Washington, DC) |
| AU | Autodesk University (online classes) |
| AU | Automatic Updates (Microsoft Windows) |
| AU | Astronomical Unit |
| AU | Auburn University (Auburn, Alabama) |
| AU | Alternate Universe |
| AU | Administrative Unit |
| AU | Aurora University |
| AU | Anna University (India) |
| AU | Ashland University |
| AU | Athabasca University |
| AU | Andrews University |
| AU | Authorized User |
| AU | Angeles University (Philippines) |
| AU | Adelphi University |
| Au | Aurum (Latin: Gold) |
| AU | Ashford University (Clinton, IA) |
| AU | Avila University |
| AU | Annamalai University (India) |
| AU | Argosy University |
| AU | Andhra University (India) |
| AU | Another Universe (comics) |
| AU | Ankara University |
| AU | Alopecia Universalis |
| AU | Associated Universities |
| AU | Alcohol Unit |
| AU | Anadolu University |
| AU | American Racing Pigeon Union (Oklahoma City) |
| AU | Arbitrary Unit |
| AU | Atomic Unit |
| AU | Atheists United |
| AU | Averett University (Danville, VA) |
| AU | Arithmetic Unit |
| AU | ATM User |
| AU | Always Usually |
| AU | Angstrom Unit |
| AU | Auxiliary Unit |
| AU | Amman University |
| AU | Associate in Underwriting (insurance) |
| AU | Unity Alliance (Nicaragua) |
| AU | Aquinas University |
| AU | Ambassador University |
| AU | Absorbance Unit |
| AU | Authors System |
| AU | Arellano University (Manila, Philippines) |
| AU | Aligarh University (India) |
| AU | Autistic/Autism |
| AU | Alignment Unit |
| AU | Analyzer Unit |
| AU | Apache University |
| AU | Araullo University |
| AU | Encoded Audio Format (file extension; Sun and NeXT) |
| AU | Auris Uterque (Latin: each ear) |
| AU | Automated Underwriter |
| AU | Authentication Unification (Sprint) |
| AU | Anställningsutskottet (Swedish: Employment Committee) |
| AU | Avionics Upper (panel) |
| AU | Adaptive Unit |
| AU | Addressee Unknown |
| AU | Accessible Unit |
| AU | Action Unit |
| AU | Aberdeen University (UK; aka University of Aberdeen; also seen as UoA) |
| AU | Adaptation Unit |
| AU | Aarhus Universit (University of Aarhus; Denmark) |
| AU | Access Unit |
| AU | About Uncirculated (numismatics; coin condition) |
| AU | Acorn User (magazine) |
| AU | Aberystwyth University (Aberystwyth, UK) |
| AU | Adamson University |