| Abbreviation | Definition |
|---|---|
| RE | Russian English |
| RM | Rhaeto-Romance |
| RN | Kirundi: A language of Niger and Congo |
| RN | Kurundi |
| RO | Romanian |
| RU | Russian |
| RW | Kinyarwanda |
| SA | Sanskrit |
| SC | Sardinian |
| SD | Sindhi |
| SF | Sentence Fragment |
| SG | Sangho |
| sgn-NI | Nicaraguan Sign Language |
| sgn-US | American Sign Language |
| SH | Serbo-croatian |
| SI | Singhalese |
| SI | Sino Indian |
| SK | Slovak |
| SL | Slovenian |
| SL | Slovenian/Slovene |