| Acronym | Meaning |
| AKDQ | Aluminum-killed Drawing Quality |
| AKH | Adipokinetic Hormone |
| AL:PE | Acidification Of Mountain Lakes: Paleolimnol. And Ecol. |
| ALA | American Library Association |
| ALA | Association For Laboratory Automation |
| ALABC | Advanced Lead Acid Battery Consortium |
| ALACE | Autonomous Lagrangian Circulation Explorer (float) |
| ALAD | Delta-aminolevulinic Acid Dehydratase (lead Poisoning Indicator) |
| ALADDIN | Atmospheric Layer And Density Distribution Of Ions And Neutrals (NASA) |
| ALAP | As Low As Possible |
| ALAP | As Low As Practical |
| ALAPCO | Association Of Local Air Pollution Control Officials |
| ALAPO | Association Of Local Air Pollution Control Officers |
| ALARA | As Low As Reasonably Achievable |
| ALARP | As Low As Reasonably Practicable |
| ALAU | Delta-aminolevulinic Acid Dehydratase In Urine (lead Poisoning Indicator) |
| ALCA | American Leather Chemists' Association |
| ALCAM | Activated Leukocyte Cell Adhesion Molecule |
| ALCHEMI | Atomic Location By Channeling Enhanced Microanalysis |
| ALCOM | Advanced Liquid Crystalline Optical Materials |
| ALCVD | Atomic Layer Chemical Vapor Deposition |
| ALD | Approximate Lethal Dose |
| ALD | Atomic Layer Deposition |
| ALE | Atmospheric Lifetime Experiment |
| ALE | Atomic Layer Epitaxy |
| ALEPH | Apparatus For LEP PHysics |
| ALEX | Aerosol LIDAR Experiment |
| ALEXIS | Array Of Low Energy X-Ray Imaging Sensors |
| ALI | Acute Lung Injury |
| ALI | Annual Limit On Intake |
| ALIAS | Aircraft Laser Infrared Absorption Spectrometer |
| ALICE | A Large Ion Collider Experiment |
| ALICE | Adiabatic Low-energy Injection And Confinement Experiment |
| ALICE | Acid-labile Isotope-coded Extractants |
| ALIPS | Automated Laser-Induced Phosphorimeter System |
| ALK | Anaplastic Lymphoma Kinase |
| ALL | Acute Lymphoblastic Leukemia |
| ALMA | Analytical Laboratory Managers Association |
| ALMA | Atacama Large Millimeter Array |
| ALMBE | Atomic Layer Molecular-beam Epitaxy |
| ALMR | Advanced Liquid Metal Reactor |
| ALMS | Atomic Line Molecular Spectroscopy |
| ALMV | Alfalfa Mosaic Virus |
| ALN | Adaptive Learning Network |
| ALOHA | Areal Location Of Hazardous Atmospheres |
| ALOMAR | Arctic Lidar Observatory For Middle Atm. Research |
| ALOS | Advanced Land Observation Satellite |
| ALOTS | Airborne Lightweight Optical Tracking System |
| ALP | Alkaline Phosphatase |
| ALPID | Analysis Of Large Plastic Incremental Deformation |