| Acronym | Meaning |
| AGRP | Agouti-related Protein |
| AGS | Alternating Gradient Synchroton |
| AGST | Above Ground Storage Tank |
| AGU | American Geophysical Union |
| AGU | Anhydroglucose Units |
| AGWSE | Association Of Ground Water Scientists And Engineers |
| AH | Aryl Hydrocarbon |
| AHA | American Heart Association |
| AHA | Anterior Hypothalamic Area |
| AHAM | American Household Appliance Manufacturers |
| AHCPR | Agency For Health Care Policy And Research |
| AHERA | Asbestos Hazard Emergency Response Act |
| AHF | Antihemophilic Factor |
| AHF | Approximate Hartree-Fock Method |
| AHG | Antihemophilic Globulin |
| AHH | Aryl Hydrocarbon Hydroxylase |
| AHM | Acutely Hazardous Materials |
| AHM | Average Hamiltonian Model Method |
| AHMM | Academy Of Hazardous Materials Management |
| AHMRTS | Automated Hazardous Materials Retrieval And Tracking System |
| AHP | Analytic Hierarchy Process |
| AHP | Average Hole-potential (method For Electronic-structure Calcns. On Mols.) |
| AHR | Airway Hyperresponsiveness |
| AHR | Aryl Hydrocarbon Receptor |
| AHRQ | Agency For Healthcare Research And Quality |
| AHSP | ΓΏ-Hemoglobin-stabilizing Protein |
| AHSV | African Horsesickness Virus |
| AHU | Air Handling Unit |
| AHW | Atomic Hydrogen Welding |
| AI | 'Agpaitic Index' And Represents The (Na2O + K2O)/Al2O3 Ratio. |
| AI | Agpaitic Index [represents The (Na2O + K2O)/Al2O3 Ratio] |
| AI | Artificial Intelligence |
| AIA | Automated Image Analysis |
| AIAA | American Institute Of Aeronautics And Astronautics |
| AIADC(3) | Ab Initio Third-order Algebraic Diagrammatic Construction Green Function Method |
| AIBS | American Institute Of Biological Sciences |
| AIC | Air Information Center |
| AIC | Acceptable Intakes For Chronic Exposure |
| AICD | Activation-induced Cell Death |
| AICE | American Institute Of Chemical Engineers |
| AICHE | American Institute Of Chemical Engineers |
| AICR | American Institute For Cancer Research |
| AICS | Australian Inventory Of Chemical Substances |
| AICUZ | Air Installation Compatible Use Zones |
| AID | Agency For International Development |
| AIDE | Annie Interactive Development Environment |
| AIDJEX | Arctic Ice Dynamics Joint Experiment |
| AIDS | Acquired Immune Deficiency Syndrome |
| AIEE | American Institute For Electrical Engineers |
| AIEMP | Ab Initio Embedding Model Potential |