| Acronym | Definition |
|---|
| HAT | How About That? |
| HAT | Hawaii Aloha Travel (est. 1997) |
| HAT | Histone Acetyltransferase (enzyme) |
| HAT | Host Access Transformation (computing) |
| HAT | Hearing Assistive Technology |
| HAT | Hardware Attached on Top (computing) |
| HAT | Horizontal Axis Turbine (energy) |
| HAT | Hazard Awareness Training (Alberta Motor Transport Association; Canada) |
| HAT | Hardware Address Translation |
| HAT | Human African Trypanosomiasis (disease) |
| HAT | Help Authoring Tool |
| HAT | High-Altitude Training |
| HAT | Health Advisory Team (various locations) |
| HAT | Highest Astronomical Tide |
| HAT | Honor Amongst Thieves |
| HAT | Hepatic Artery Thrombosis |
| HAT | Housing Action Trust (UK) |
| HAT | Height Above Touchdown |
| HAT | Hospitality Accommodations of Texas (Austin, Texas) |
| HAT | Hrvatska Agencija Za Telekomunikacije (Croatian Telecommunication Agency) |
| HAT | Head, Arms, Trunk |
| HAT | Height Above Terrain |
| HAT | Home Automated External Defibrillator Trial (clinical trial) |
| HAT | History of Approximation Theory |
| HAT | Housing Assistance for Teachers (Mississippi) |
| HAT | Host Access Table |
| HAT | Hyper-Active Thyroid |
| HAT | Hardware Acceptance Test |
| HAT | High-Alarm Threshold |
| HAT | Handling and Archiving Tool |
| HAT | Hizam Al-Taawun (Arab belt of cooperation) |
| HAT | Heavy Assault Team |
| HAT | High-Angle Threat |
| HAT | Handicapped Awareness Trail (activity, Camp Yawgoog, BSA) |
| HAT | HUMINT(Human Intelligence) Augmentation Team (US DoD) |
| HAT | Harbor Acceptance Trial |
| HAT | Reproductive Health for Quality of Life Development Association of Thailand |
| HAT | Harpoon as a Target |
| HAT | High Altitude Transition |