| Abbreviation | Definition |
|---|---|
| SG | Sub-Group |
| SGF | Spherical Gaussian Function |
| SH | The Subspace Of H |
| SI | The international system of units |
| SIAM | Society for Industrial and Applied Mathematics |
| SIAM | Society of Industrial and Applied Mathematics |
| SIM | Simple Integration Method |
| SIMI | Secondary Initiative For Mathematics Improvement |
| SIMO | South India Math Olympiad |
| SIMO | South Indian Maths Olympiad |
| SIMOC | Singapore International Mathematics Olympiad Challenge |
| sin | sine |
| SINH | Hyperbolic Sine |
| SIPVP | Symmetric Independent Private-Values Paradigm |
| SIQR | Semi-InterQuartile Range |
| SIR | Sampling, Importance, Re-sampling |
| SIR | Sort Interval Recursive |
| SIR(s) | standardized incidence ratio(s) |
| SIS | Small Inducible Secreted |
| SIT | Semi Implicit And Traditional |