| Abbreviation | Definition |
|---|---|
| RUM | Romanian |
| RUN | Rundi |
| RUS | Russian |
| SAD | Sandawe |
| SAE | Standard American English |
| SAG | Sango |
| SAH | Sahara |
| SAH | Yakut |
| SAI | South American Indian (Other) |
| SAL | Salishan Languages |
| SAM | Samaritan Aramaic |
| SAN | Sanskrit |
| SAS | South Asia |
| SCO | Scots |
| SCR | Serbo-Croatian |
| SEA | Southeast Asia |
| SEL | Selkup |
| SEM | Semitic - Other |
| SEM | Southern Europe and Mediterranean |
| SGA | Old Irish (to 900) |