| Abbreviation | Definition |
|---|---|
| SIMI | Students Islamic Movement Of India |
| SIMS | Services Institute of Medical Sciences |
| SIMS | Student Information Management System |
| SIN | Student Information Network |
| SIN | Student Infraction Notice |
| SINU | Solomon Islands National University |
| SIO | Students Islamic Organisation of India |
| SIO | Students Islamic Organization of India |
| SIP | Spring Intensive Program |
| SIP | Student Information Portal |
| SIP | Student Initiated Project |
| SIPP | Student Installment Payment Plan |
| SIPRI | Stockholm International Peace Research Institute |
| SiPS | Student Information and Performance System |
| SIPT | Sokhumi Institute of Physics and Technology |
| SIQ | Slovenian Institute of Quality and Metrology |
| SIQR | Summer Institute in Qualitative Research |
| SIR | Science Information Robot |
| SIR | Simulated Intelligence Robotics |
| SIR | Student Issues Roundtable |