| Acronym | Meaning |
| SPLITT | Split-flow Thin [fractionation] |
| SPLP | Synthetic Pptn. Leaching Procedure |
| SPM | Scanning Probe Microscopy |
| SPM | Scanning Proton Microprobe |
| SPM | Suspended Particulate Matter |
| SPMC | Stationary Phase Monte Carlo |
| SPMD | Solar Powered Membrane Distillation |
| SPMD | Semipermeable Membrane Device |
| SPME | Solid-Phase Microextraction |
| SPMN | Soil Potentially Mineralizable Nitrogen |
| SPMP | Scanning Proton Microprobe |
| SPO | Spin Projection Operator |
| SPORE | Solid-Phase Organic Reactions |
| SPOS | Single-particle Optical Sensing |
| SPOS | Solid Phase Organic Synthesis |
| SPOT | Satellite Pour L'Observation De La Terre |
| SPP | Surface Plasmon Polariton |
| SPP | Suspended Particulate Phase |
| SPPA | Self-consistent Polarization Propagator Approximation |
| SPPD | Spin Polarized Photoelectron Diffraction |
| SPPES | Spin Polarized Photoelectron Spectroscopy |
| SPPS | Solid Phase Peptide Synthesis |
| SPQC | Series Piezoelectric Quartz Crystal |
| SPR | Stroboscopic Pulse Radiolysis |
| SPR | Surface Plasmon Resonance |
| SPRI | Solid-phase Reversible Immobilization |
| SPRI | Surface Plasmon Resonance Imaging |
| SPRKKR | Spin-polarized Relativistic Korringa-Kohn-Rostoker |
| SPS | Spark Plasma Sintering |
| SPS | Sucrose-phosphate Synthase |
| SPS | Surface Photovoltage Spectroscopy |
| SPT | Selective Polarization-transfer |
| SPT | Standard Penetration Test |
| SPU | Segmented Polyurethane |
| SPUMPN | Single-annihilation Procedure Unrestricted Moeller-Plesset Nth-order |
| SPUPS | Spin Polarised Ultraviolet Photoelectron Spectroscopy |
| SPV | Surface Photovoltage |
| SPW | Symmetrized Plane Wave |
| SQC | Sediment Quality Criteria |
| SQC | Statistical Quality Control |
| SQCC | Semiclassical Quantization (by) Circuit Counting |
| SQF | Second-quantized Formulation (in Many-body Quantum Theory) |
| SQG | Small Quantity Generator |
| SQL | Standard Quantum Limit |
| SQM | Scaled Quantum Mechanics (in Ab Initio Calcns.) |
| SQRD | Square Root Darwin Term (correction To T And V Operator) |
| SQUID | Superconducting Quantum Interference Device |
| SQW | Single Quantum Well |
| SR-CC | Single Reference-CC |
| SR-CCD | Single Reference-CCD |