| Abbreviation | Definition |
|---|---|
| S-B | Soviet-Bloc |
| SC | Sacramento Field Office |
| SC | Special Clerk |
| SCC | Special Coordination Committee |
| SCU | Special Crimes Unit |
| SCUM | Socially Cognitive Unified Murderers |
| SD | San Diego Field Office |
| SDFI | Secure Digital Forensic Imaging |
| SDNT | Specially Designated Narcotics Trafficker |
| SF | San Francisco Field Office |
| SI | Site Investigation |
| SJ | San Juan Field Office |
| SK | St. Louis Field Office |
| SM | Security Matter |
| SM | Summary |
| SMUN | Soviet Mission to the United Nations |
| SODAC | SOviet Diplomatic ACtivities |
| SOG | Seat Of Government |
| SOM | Secret Organized Mafia |
| SOP | Standard Operating Procedure |