| Abbreviation | Definition |
|---|---|
| SLIC | Senior Labour Inspectors Committee |
| SLIC | Senior Labour Inspectors’ Committee |
| SLRFU | Sri Lanka Rugby Football Union |
| SLU | South Lake Union |
| SLUS | South Lake Union Streetcar |
| SLUT | South Lake Union Transit |
| SLUT | South Lake Union Trolley |
| SLWP | South London Waste Partnership |
| SMCU | San Mateo Credit Union |
| SMCU | Seattle Metropolitan Credit Union |
| SMCU | Southern Mass Credit Union |
| SMOU | Singapore Maritime Officers Union |
| SMSU | Santos Manuel Student Union |
| SMSU | Smith Memorial Student Union |
| SMTU | Singapore Malay Teachers Union |
| SMUD | Société de Musique Union de Distroff |
| SMUG | Saints Monthly Union of Givers |
| SNAFU | Southern Nevada Ale Fermenters Union |
| SNAFU | Southern Northern Atlantic Forensics Union |
| SNU | Spiritualists' National Union |