| Acronym | Meaning |
| APL | Alternative Pollutant Limits |
| APL | Acute Promyelocytic Leukemia |
| APLG | Antisymmetrized Product Of Localized Geminals (wave Function) |
| APLI | Atmospheric Pressure Laser Ionization |
| APLR | Annual Pollutant Loading Rate |
| APM | Airborne Particulate Matter |
| APM | Acoustic Plate Mode |
| APM | Atom Probe Microanalysis |
| APME | Association Of Plastics Manufacturers In Europe |
| APMI | American Powder Metallurgy Institute |
| APMP | Acid Precipitation Mitigation Program |
| APN | Aminopeptidase N |
| APNEA | Active Passive Neutron Examination And Assay |
| APNO | Atomic Pair Natural Orbital |
| APO | Aq.-phase Oxidn. |
| APO B | Apolipoprotein B |
| APOE | Apolipoprotein E |
| APOMA | American Precision Optics Manufacturers Association |
| APP | Acoustic Phase Plate |
| APP | Amyloid Precursor Protein |
| APPH | Auger Peak To Peak Height |
| APPI | Atmospheric Pressure Photoionization |
| APPM | Atomic Parts Per Million |
| APR | Air-Purifying Respirator |
| APR | Acoustic Paramagnetic Resonance |
| APRE | Acute-phase-responsive Element |
| APRF | Army Pulse Radiation Facility |
| APRF | Acute Phase Response Factor |
| APRIL | A Proliferation-inducing Ligand |
| APRR | Adiabatic Passage Rotational-resonance |
| APS | Ammonium Persulfate |
| APS | Advanced Photon Source |
| APS | American Physical Society |
| APS | Active Pixel Sensor |
| APS | Adiabatic Pseudopotential |
| APS | Aerodynamic Particle Sizer |
| APS | Air Plasma Spraying |
| APS | Antiphospholipid Syndrome |
| APS | Appearance Potential Spectroscopy |
| APS | Atom Probe Spectroscopy |
| APS | Autocorrelation Photon Spectroscopy |
| APSA | Advanced Photovoltaic Solar Array |
| APSG | Antisymmetrized Product Of Separated Geminals |
| APSG | Antisymmetrized Product Of Spin Geminals Method |
| APSG | Antisymmetrized Product Of Strongly Orthogonal Geminals (variant Of Multiconfiguration Self-consistent Field Method) |
| APSGF | Antisymmetrical Product Of Strongly Orthogonal Group Functions (a Wave Function) |
| APSIS | Athenian Photochem. Smog Intercomparison Of Simulations |
| APSTNG | Associated-particle Sealed-tube Neutron Generator |
| APT | Accelerator Production Of Tritium |
| APT | Analytic Perturbation Theory |