| Acronym | Meaning |
| PMN | Lead Magnesium Niobate |
| PMN | Polymorphonuclear Leukocyte |
| PMN | Premanufacture Notice |
| PMO | Periodic Mesoporous Organosilica |
| PMO | Perturbational Molecular Orbital |
| PMO | Perturbed Morse Oscillator (model Potential) |
| PMOS | P-channel Metal Oxide Semiconductor |
| PMP | Peroxisomal Membrane Protein |
| PMP | Powder Melting Process |
| PMP | Project Management Plan |
| PMP2 | (spin) Projected Moeller-Plesset Second-order (perturbation Theory) |
| PMP4 | (spin) Projected Moeller-Plesset Fourth-order (perturbation Theory) |
| PMPIN | Pre-Manufacturing And Pre-Importation Notification |
| PMPO | Perturbed Morse Pekeris Oscillator (model Potential) |
| PMR | Proportional Mortality Ratio |
| PMR | Proton Magnetic Resonance |
| PMS | Premenstrual Syndrome |
| PMSR | Pairwise-mixing Stirred Reactor |
| PMT | Pasteurella Multocida Toxin |
| PMT | Photomultiplier Tube |
| PMTDI | Provisional Maximum Tolerable Daily Intake |
| PMTR | Photomodulated Thermoreflectance |
| PNA | Paraffins, Naphthenes, And Aromatics (in Petroleum Analysis) |
| PNA | Peanut Agglutinin |
| PNA | Peptide Nucleic Acid |
| PNA | Polynuclear Aromatic Compound(s) |
| PNC | Parity Nonconservation |
| PNDDO | Partial Neglect Of Diatomic Differential Overlap |
| PNDO | Partial Neglect Of Differential Overlap |
| PNEC | Predicted No-effect Concentration |
| PNET | Primitive Neuroectodermal Tumor |
| PNGV | Partnership For A New Generation Of Vehicles |
| PNH | Paroxysmal Nocturnal Hemoglobinuria |
| PNN | Lead Nickel Niobate |
| PNN | Probabilistic Neural Network |
| PNNL | Pacific Northwest National Laboratory |
| PNO | Pair Natural Orbital |
| PNO | Pseudonatural Orbital |
| PNO-CE | Pseudonatural Orbital-configuration Expansion |
| PNO-CEPA | Pseudonatural Orbital-coupled Electron Pair Approximation |
| PNO-CI | Pseudonatural Orbital-configuration Interaction |
| PNP | Purine Nucleoside Phosphorylase |
| PNR | Polarized Neutron Reflection |
| PNRA | Photon-tagged Nuclear Reaction Analysis |
| PNS | Peripheral Nervous System |
| PO | Polarization Orbital |
| PO | Projection Operator |
| PO-DVR | Potential Optimized-discrete Variable Representation |
| PO-DVR-REV | Potential Optimized-discrete Variable Representation-ray Eigenvector |
| PO-MO | Pars Orbital-MO |