| Acronym | Meaning |
| SPCP | Surface Discharge Induced Plasma Chemical Process |
| SPDES | New York State Pollutant Discharge Elimination System |
| SPDM | Single-particle Density Matrix |
| SPDT | Single Point Diamond Turning |
| SPDT | Single-pole Double-throw (switch) |
| SPE | Solar Proton Event |
| SPE | Solid Phase Electrolyte |
| SPE | Solid Phase Epitaxy |
| SPE | Solid Phase Extraction |
| SPE | Solid Polymer Electrolyte |
| SPEAR | Stanford Positron Electron Accelerating Ring |
| SPECM | Scanning Photoelectrochemical And Electrochemical Microscopy |
| SPECT | Single Photon Emission Computerized Tomography |
| SPEED | Selective Potentiostatic Etching By Electrolytic Dissolution |
| SPEED | SiRNA Prodn. By Enzymatic Engineering Of DNA |
| SPEELS | Spin-polarized Electron Energy Loss Spectroscopy |
| SPEG | Solid Phase Epitaxial Growth |
| SPELEEM | Spectroscopic PhotoEmission And Low Energy Electron Microscope |
| SPELL | Spectral Eulerian Lagrangian Model |
| SPEM | Scanning Photoemission Microscopy |
| SPEMC-SCF | Selected Paired Excitational Expansion Multiconfiguration-SCF |
| SPES | Step Potential Electrochemical Spectroscopy |
| SPF | Simons-Parr-Finlan (potential Function) |
| SPF | Specific Pathogen-free |
| SPF | Sun Protection Factor |
| SPF | Superplastic Forming |
| SPFD | Simons-Parr-Finlan-Dunham (interat. Potential) |
| SPFM | Scanning Polarization Force Microscopy |
| SPFS | Surface Plasmon Fluorescence Spectroscopy |
| SPG | Shirasu Porous Glass |
| SPG | Sequential Product (of) Geminals |
| SPHEM | Superfund Public Health Evaluation Manual |
| SPHF | Spin-polarized Hartree-Fock |
| SPHINCS | Sequential PHoton Interrogation And Neutron Counting Signatures |
| SPI | Society For The Plastics Industry |
| SPI | Soy Protein Isolate |
| SPICE | Simulation Program With Integral Circuit Emphasis |
| SPIE | Society Of Photo-Optical Instrumentation Engineers |
| SPIES | Surface Penning Ionization Electron Spectroscopy |
| SPIN | Silica Phase-immobilized Nitroxide |
| SPINDO | Spectroscopic Potentials Adjusted Intermediate Neglect Of Differential Overlap |
| SPINOE | Spin Polarization-induced Nuclear Overhauser Effect |
| SPIO | Superparamagnetic Iron Oxide |
| SPIPES | Spin Polarized Inverse Photoemission Spectroscopy |
| SPIRIT | Spatial IR Imaging Telescope |
| SPIRIT | Single Photon Ionization Resonance Ionization To Threshold |
| SPIS | Surface Penning Ionization Spectroscopy |
| SPL | Spent Potliner |
| SPLEED | Spin Polarized Low-energy Electron Diffraction |
| SPLEEM | Spin-polarized Low-energy Electron Microscopy |