| Abbreviation | Definition |
|---|---|
| SI | Silly I |
| SI | Simply Irresistible |
| SI | Stupid Idiot |
| SIAP | Sorry If Already Posted |
| SIBS | Send It Back Saturday |
| SIBW | Strong Independant Black Woman |
| SIC | Said In Content |
| SIC | Said In Context |
| SIDA | Syndrome Imagined to Discourage Amour |
| SIDLT | Stop I Don't Like That |
| SIEM | Security Insight and Event Management |
| SIG | Said In Gest! |
| SIG | Sorority Interest Group |
| SIG | Super Intelligent Geeks |
| SIMI | Sorry-I-Missed-It |
| SIN | Self Imposed Nonsense |
| SIN | Spill It Now |
| SINC | Single Income No Cooking |
| SIOM | So It's On Me |
| SIP | Smiling In Public |