| Acronym | Meaning |
| SSMS | Spark Source Mass Spectrometry |
| SSNTD | Solid-state Nuclear Track Detector |
| SSOP | Sequence Specific Oligonucleotide Probe |
| SSP | Sequence Specific Primer |
| SSPG | Steady-state Plasma Glucose |
| SSPM | Scanning Surface Potential Microscopy |
| SSQM | Supersymmetric Quantum Mechanics |
| SSQW | Strained Single Quantum Well |
| SSR | Simple Sequence Repeat |
| SSRI | Selective Serotonin Reuptake Inhibitor |
| SSRL | Stanford Synchrotron Radiation Laboratory |
| SSRM | Scanning Spreading Resistance Microscopy |
| SSRS | Subtracted Shifted Raman Spectroscopy |
| SSRTF | Solid Surface Room Temperature Fluorescence |
| SSRTP | Solid-surface Room-temperature Phosphorimetry |
| SSSA | Soil Science Society Of America |
| SSSD | Small-scale, Short-duration |
| SSSP | Solid-state Shear Pulverization |
| SSSP | Simulation Of Single Sludge Processes |
| SST | Sea Surface Temperature |
| SSTI | Small System Technol. Initiative (USEPA) |
| SSTL | Singwi Sjolander Tosi Land (interatomic Potential) |
| SSULI | Special Sensor Ultraviolet Limb Imager |
| SSUSI | Special Sensor UV Spectrographic Imager |
| SSUWP | Single Sided Universal Wet Processor |
| SSW | Solid-state Welding |
| ST4CCD | Coupled Cluster (with) Double (substitutions And) Single (and) Triple (substitutions Incorporated Via) Fourth-order (perturbat |
| STA | Science And Technology Agency (Japan) |
| STA | Simultaneous Thermal Analysis |
| STA | Single-transition Approximation |
| STAD | Simple Town Air Dispersion Model (of Air Pollution) |
| STAIRS | Storage And Information Retrieval System |
| STAPPA | State And Territorial Air Pollution Program Administrators |
| STAR | Solenoidal Tracker At RHIC |
| STARR | Staged Approach To Risk Reduction |
| STARS | Strategic Targeting Activities Reporting System |
| START | Strategic Arms Reduction Treaty |
| STAS | Scientific And Technical Attribute And Element Set |
| STAT | Signal Transducer And Activator Of Transcription |
| STAT | Slotted Tube Atom Trap |
| STATE | Sulfur Transport And Transformation In The Environment |
| STB | Semiempirical Tight Binding |
| STBF | Slater-type Basis Function |
| STCA | Simplified Traveling-cluster Approxn. (for Electronic Structure) |
| STD | Safely Tolerated Dose |
| STD | Sexually Transmitted Disease |
| STE | Self-trapped Exciton |
| STE | Septic Tank Effluent |
| STEAM | Stratosphere-Troposphere Exchange And Climate Monitor |
| STEAM | Stimulated Echo Acquisition Mode |