| Abbreviation | Definition |
|---|---|
| SIOP | Society for Industrial & Organizational Psychology |
| SIPA | Structural Insulated Panel Association |
| SIPMM | Singapore Institute of Purchasing Materials Management |
| SIPMM | Singapore Institute of Purchasing & Materials Management |
| SIPT | Société internationale de la photogrammétrie et télédétection |
| SIPTU | Services Industrial Professional and Technical Union |
| SIR | Society of Interventional Radiology |
| SIRA | Society of Information Risk Analysts |
| SIRA | Southern Indiana REALTORS Association |
| SIRB | Siriraj Institutional Review Board |
| SIRIM | Standards and Industrial Research Institute of Malaysia |
| SISO | Simulation Interoperability Standards Organization |
| SITA | Spirit Industry Trade Association |
| SITE | Society of Incentive Travel Executives |
| SITI | Software and Information Technology of Iowa |
| SIU | Seafarers International Union |
| SJI | Steel Joist Institute |
| SJS | Self Job Solutions |
| SJTA | San Jose Teachers Association |
| SJTA | Southern Jewelry Travelers Association |