| Acronym | Meaning |
| ABEP | Acetate Buffer Extraction Procedure |
| ABES | Alliance For Balanced Environmental Solutions |
| ABET | Accreditation Board For Engineering And Technology |
| ABF | Activated Biofilter |
| ABG | Arterial Blood Gas |
| ABHP | American Board Of Health Physics |
| ABI | Automated Ball Indentation |
| ABIH | American Board Of Industrial Hygienists |
| ABL | Atmospheric Boundary Layer |
| ABLE | Amazon Boundary Layer Experiment |
| ABLE | Arctic Boundary Layer Expedition |
| ABLE | Atmospheric Boundary Layer Experiments |
| ABMA | American Boiler Manufacturers Association |
| ABMR | Atomic Beam Magnetic Resonance |
| ABMT | Autologous Bone Marrow Transplantation |
| ABO | Adiabatic Born-Oppenheimer (wave Functions) |
| ABO | Antibonding Bond Orbital |
| ABP | Androgen-binding Protein |
| ABPA | Allergic Bronchopulmonary Aspergillosis |
| ABR | Acrylate-butadiene Rubber |
| ABR | Advanced Breeder Reactor |
| ABR | Anaerobic Baffled Reactor (for Wastewater Treatment) |
| ABR | Auditory Brainstem Response |
| ABRE | Abscisic Acid-responsive Element |
| ABRF | Association Of Biomolecular Resource Facilities |
| ABS | Acrylonitrile-Butadiene-Styrene Copolymer (REG: 9003569) |
| ABS | Arc Bond Sputter |
| ABS | Alkylbenzene Sulfonates (anionic Surfactants) |
| ABS | Atomic Beam Scattering |
| ABSA | American Biological Safety Association |
| ABSORB | Arctic Beaufort Sea Oilspill Research Body |
| ABTS | 2,2'-azinobis(3-ethyl-benzthiazoline-6-sulfonic Acid) |
| ABWAG | Abwasserabgabengestres (Germany Wastewater Discharge Law Regulates Cost Per Volume) |
| ABWR | Advanced Boiling Water Reactor |
| ABXP | Ab Initio Dv-x.alpha. Point Charge Approxn. (in Solid Surface Electronic Structure Calcn.) |
| AC | Alternating Current |
| ACA | American Crystallographic Association |
| ACAID | Anterior Chamber Associated Immune Deviation |
| ACAMS | Automatic Continuous Air Monitoring System |
| ACANTO | Activation Analysis For Toxicology |
| ACAR | Angular Correlation Of Annihilation Radiation |
| ACAT | Acyl-CoA: Cholesterol Acyltransferase |
| ACATS | Airborne Chromatograph For Atmospheric Trace Species |
| ACBM | Advanced Cement-Based Materials |
| ACBM | Asbestos Containing Building Material |
| ACBP | Acyl-CoA Binding Protein |
| ACBS | Aqueous-ceramic Binding Suspension |
| ACC | 1-aminocyclopropane-1-carboxylic Acid |
| ACC | American Chemistry Council |
| ACC | American College Of Cardiology |