| Acronym | Meaning |
| ACC | Antarctic Circumpolar Current |
| ACC | Acetyl-CoA Carboxylase |
| ACC | Approximate Coupled Cluster |
| ACC | Aquifer Contamination Control |
| ACC-IOS | Azimutal Close Coupled-infinite Order Sudden |
| ACCAD | Advisory Committee On Climate Applications And Data |
| ACCCI | American Coke And Coal Chemicals Institute |
| ACCD | Approximate Double Substitution Coupled Cluster Method |
| ACCDPPA | Approx. Coupled Cluster With Double Excitations Polarization Propagator Approxn. |
| ACCLAIM | Antarctic Circumpolar Current Levels From Altimetry And Island Measurement |
| ACCP | Atlantic Climate Change Program (of NOAA |
| ACCR | Activated Carbon Catalytic Reduction |
| ACCSA | Adiabatic Capture Centrifugal Sudden Approximation |
| ACD | Atmospheric Chemistry Division |
| ACD | Available Chemicals Directory |
| ACD | Allergic Contact Dermatitis |
| ACD | Annealed Cold Drawn |
| ACE | Aerosol Characterization Experiment |
| ACE | Alliance For Clean Energy |
| ACE | Acidity In Cloud Experiment |
| ACE | Affinity Capillary Electrophoresis |
| ACE | Alternating Conditional Expectations |
| ACE | Angiotensin-converting Enzyme |
| ACE | Atmospheric Collection Equipment |
| ACE-ASIA | Aerosol Characterization Expts.-Asia |
| ACE-I | Angiotensin Converting Enzyme Inhibitor |
| ACEC | Areas Of Critical Environmental Concern |
| ACEEE | American Council For An Energy Efficient Economy |
| ACEI | Angiotensin Converting Enzyme Inhibitor |
| ACEL | A.c. Electroluminescent |
| ACEMS | Angular Conversion Electron Moessbauer Spectroscopy |
| ACERC | Advanced Combustion Engineering Research Center |
| ACES | Annual Cycle Energy Storage System |
| ACF | Activated Carbon Fiber(s) |
| ACF | Activated Coke Fines |
| ACF | Anticoagulant Factor |
| ACF | Autocorrelation Function |
| ACFB | Atmospheric Circulating Fluidized Bed |
| ACFM | Actual Cubic Feet Per Minute |
| ACGCSA | Adiabatic Capture Global Centrifugal Sudden Approximation |
| ACGIH | American Conference Of Governmental Industrial Hygienists |
| ACH | Air Changes Per Hour |
| ACHMM | Academy Of Certified Hazardous Materials Managers |
| ACHRE | Advisory Committee On Human Radiation Experiments |
| ACI | Alloy Casting Institute |
| ACI | Acceptable Chronic Intake |
| ACID | Acidification Chemistry Information Database |
| ACIL | American Council Of Independent Laboratories |
| ACIMS | Active Chemical Ionization Mass Spectroscopy |
| ACIOSA | Adiabatic Capture Infinite Order Sudden Approximation |