word | | Country name |
| Saint | Saint Vincent and the Grenadines | conventional long form: none conventional short form: Saint Vincent and the Grenadines |
| Sak | Georgia | conventional long form: none conventional short form: Georgia local long form: none local short form: Sak'art'velo former: Georgian Soviet Socialist Republic |
| Saltanat | Oman | conventional long form: Sultanate of Oman conventional short form: Oman local long form: Saltanat Uman local short form: Uman former: Muscat and Oman |
| Salvador | El Salvador | conventional long form: Republic of El Salvador conventional short form: El Salvador local long form: Republica de El Salvador local short form: El Salvador |
| Samajaya | Sri Lanka | ... Socialist Republic of Sri Lanka conventional short form: Sri Lanka local long form: Shri Lamka Prajatantrika Samajaya di Janarajaya/Ilankai Jananayaka Choshalichak Kutiyarachu local short form: Shri Lamka/Ilankai former: Serendib, Ceylon |
| Samoa | American Samoa | conventional long form: Territory of American Samoa conventional short form: American Samoa abbreviation: AS |
| Samoa | Samoa | conventional long form: Independent State of Samoa conventional short form: Samoa local long form: Malo Sa'oloto Tuto'atasi o Samoa local short form: Samoa former: Western Samoa |
| San | San Marino | conventional long form: Republic of San Marino conventional short form: San Marino local long form: Repubblica di San Marino local short form: San Marino |
| Sanaa | Yemen | ... long form: Al Jumhuriyah al Yamaniyah local short form: Al Yaman former: Yemen Arab Republic [Yemen (Sanaa) or North Yemen] and People's Democratic Republic of Yemen [Yemen (Aden) or South Yemen |
| Sandwich | South Georgia and the South Sandwich Islands | conventional long form: South Georgia and the South Sandwich Islands conventional short form: South Georgia and South Sandwich Islands abbreviation: SGSSI |