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| Particle Particle Size Parts Per Million (Ppm) Pathogen Peat Pectine Peptide Permeability Pesticides Pext Ph Phagocyte Polymer Prebiotic Probiotic Protein (Protid) Protein-Prion |
| A minute unit of matter, usually a single crystal or of regular shape with a specific gravity approximating that of a single crystal. In physics, one of various extremely small constituents of matter. |