| PEEL | Programmable Electrically Eraseable Logic |
| PEELS | Parallel Electron Energy Loss Spectroscopy |
| PEM | Photo Elastic Modulator |
| PERM | Pre-Embossed Rigid Magnetic |
| PERT | Program evaluation review technique |
| PES | Photoelectron spectroscopy |
| PET | Post-etch treatment |
| peta | 1.00E+15 (1,000,000,000,000,000/1; symbolized by the prefix P) |
| PETEOS | Plasma-enhanced tetraethylosilicate |
| PFA | Perfluoroalkoxy |
| PFC | Perfluorocompound; Perfluorocarbon |
| PFN | Pulse forming network |
| PFPE | Perfluorinated polyether |
| PFR | Plug-flow reactor |
| PFTQ | Partnering for Total Quality |
| PGA | Pin grid array |
| PGI | Purge gas inlet |
| P-GILD | Projection gas immersion laser doping |
| PGM | Portable greymap image format |
| PGT | Princeton Gamma Tech |
| PH3 | Phosphine |
| PHEEM | Photoelectron-emission Microscopy |
| pHEMT | Pseudomorphic HEMT |
| PHIGS | Programmer's Hierarchical Interface Graphics Standard |
| PHP | Personal Handy Phone |
| PHY | Physical Layer |
| PI | Proportional integral |
| PIA | Parallel Interface Adapter |
| PIC | PC Paint image format; Peripheral Interrupt Controller; Peripheral Interface Controller; Peripheral Interface Circuit |
| pico | 1.00E-12 (1/1,000,000,000,000; symbolized by the prefix p) |
| PICTS | Photo-Induced Current Transient Spectroscopy |
| PID | Proportional Integral Derivative; Process-Induced Defect; Photo-Imageable Dielectric; Packet ID |
| PIH | Pin In Hole |
| PIII | Plasma Immersion Ion Implantation |
| PIN | P-type/Insulator/N-type; Personal Identification Number |
| PIND | Particle Impact Noise Detection |
| PIO | Parallel Input Output |
| PIP | Process-Induced Particles; Picture-In-Picture |
| PIPO | Parallel In Parallel Out |
| PISO | Parallel In Serial Out |
| PIV | Peak Inverse Voltage; Post Indicator Valve |
| PIXE | Particle Induced X-ray Emission |
| PKCS | Public Key Cryptography Standards |
| PKI | Public Key Infrastructure |
| PKIX | IETF Working Group 'Public Key Infrastructure |
| PL | Photo Luminescence |
| PLA | Programmable Logic Array |
| PLC | Programmable Logic Controller |
| PLCC | Plastic Leaded Chip Carrier |
| PLD | Programmable Logic Device |
| PLE | Photo Luminescence Excitation |
| PLL | Phase Locked Loop; Plasma lockload |
| PLS | Partial least squares; Projection of latent structures |
| PLTV | Percentage Local Thickness Variation |
| PLY | Photolimited yield |
| Pm | Promethium |
| PM | Preventive maintenance; Process module; Post meridiem (after noon) |
