| Acronym | Meaning |
| PQFP | Plastic Quad Flat Package |
| PQL | Practical Quantitation Levels (of Pollutants |
| PR | Preliminary Review |
| PRA | Probabilistic Risk Assessment |
| PRA | Plasma Renin Activity |
| PRB | Permeable Reactive Barrier |
| PRBS | Pseudo-random Binary Sequence |
| PRCPTS | Primary Reactor Coolant Pump Trip System |
| PRDA | Program Research And Development Announcement |
| PRDDO | Partial Retention Of Diatomic Differential Overlap |
| PRE | Pitting Resistance Equivalent |
| PRE | Proton Relaxation Enhancement |
| PRECP | Processing Emissions By Cloud And Precipitation (DOE Program) |
| PREELS | Position-resolved Electron Energy Loss Spectroscopy |
| PREEN | Pacific Rim Energy And Environment Network |
| PREM | Preliminary Ref. Earth Model |
| PRENFLO | PRessurized ENtrained FLOw (process) [combustion And Gasification] |
| PREP | Plasma Rotating Electrode Process |
| PRESS | Point Resolved Spectroscopy |
| PRESS | Prediction Error Sum Of Squares |
| PRESTO | Prediction Of Radiological Effects To Shallow Trench Operation |
| PREVENT | Pacific Northwest Regional Visibility Expt. Using Natural Tracers |
| PRF | Pulse Repetition Frequency |
| PRFT | Partially Relaxed Fourier Transform |
| PRIMA | Pattern Recognition By Independent Multicategory Analysis |
| PRIME | Plume Rise Model Enhancements |
| PRIME | Purdue Rare Isotope Measurement Laboratory |
| PRINS | Primed In Situ DNA Synthesis |
| PRISM | Power Reactor Innovative Small Module |
| PRISM | Parameter-related Internal Standard Method |
| PRM | Primary Reference Material |
| PRMO | Partially Restricted Molecular Orbital |
| PROACT | Proactive Respirometric Operational And Control Technology |
| PROC | Photochemically Reactive Organic Compound(s) |
| PROM | Programmable Read-only Memory |
| PROW | Protein Reviews On The Web |
| PROWL | Protein Information Retrieval Online World Wide Web Lab |
| PROX | Preferential CO Oxidn. |
| PRP | Platelet-rich Plasma |
| PRP | Potentially Responsible Party (Superfund) |
| PRP | Proline-rich Protein |
| PRP | Prion Protein |
| PRPP | Phosphoribosyl Pyrophosphate |
| PRRSV | Porcine Reproductive And Respiratory Syndrome Virus |
| PRS | Perturbed Rotational State (method For Ion-mol. Collisions) |
| PRT | Platinum Resistance Thermometer |
| PRTD | Proportional Residence Time Distribution (of Liquid Streams In Equalization Basins In WWT) |
| PRTR | Pollutant Release And Transfer Register |
| PRV | Pseudorabies Virus |
| PRZM | Pesticide Root Zone Model |