| Acronym | Meaning |
| PLC | Planar Lightwave Circuit |
| PLC | Polymer Liquid Crystal |
| PLC | Preparative (thin) Layer Chromatography |
| PLCC | Plastic Leadless Chip Carrier |
| PLD | Programmable Logic Device |
| PLD | Pulsed Laser Deposition |
| PLDA | Piecewise Linear Discriminant Analysis |
| PLDMR | Photoluminescence Detected Magnetic Resonance |
| PLE | Photoluminescence Excitation |
| PLED | Polymer Light Emitting Diode |
| PLFA | Phospholipid Fatty Acid |
| PLI | Process Loading Intensity (of Biological Reactors) |
| PLID | Pulsed Laser Induced Desorption |
| PLIF | Planar Laser Induced Fluorescence |
| PLIRRA | Pollution Liability Insurance And Risk Reduction Act |
| PLL | Phase Locked Loop |
| PLM | Polarized-light Microscopy |
| PLO | Partially Localized Orbital |
| PLOT | Porous Layer Open Tubular (capillary Column For Gas Chromatography) |
| PLS | Partial Least Squares |
| PLSR | Partial Least-squares Regression |
| PLT | Lead Lanthanum Titanate |
| PLTD | Phospholipid Transfer Protein |
| PLUARG | Pollution From Land Use Activities Reference Group |
| PLY | Photoluminescence Yield |
| PLZT | Lead Lanthanum Zirconate Titanate |
| PM | Particulate Matter |
| PM10 | Particulate Matter |
| PM3 | Third-parametric Method |
| PMA | Pharmaceutical Manufacturers Association |
| PMA | Phorbol Myristate Acetate |
| PMAD | Power Management And Distribution (system) (of Space Station) |
| PMAMS | Patterned Multi-array |
| PMC | Permanently Manned Capability (of Space Station) |
| PMC | Polymer Matrix Composite |
| PMC | Percent Modern Carbon |
| PMC-SCF | Pair Multiconfiguration-SCF (with Electron Pair Optimization) |
| PMCC | Pensky-Martens Closed Cup |
| PMDA | Pyromellitic Dianhydride |
| PMDL | Practical Method Detection Limit |
| PMEL | Pacific Marine Environmental Laboratory |
| PMF | Positive Matrix Factorization |
| PMF | Potential Of Mean Force |
| PMF | Progressive Massive Fibrosis |
| PMF | Proton Motive Force |
| PMIRRAS | Polarization Modulation Infrared Reflection Absorption Spectroscopy |
| PML | Polymer Multi Layer |
| PML | Promyelocytic Leukemia |
| PMLG | Phase Modulated Lee-Goldburg (NMR Spectrometry) |
| PMMA | Poly (methyl Methacrylate) |