word | | Country name |
| form | South Georgia and the South Sandwich Islands | conventional long form: South Georgia and the South Sandwich Islands conventional short form: none abbreviation: SGSSI |
| form | Spain | conventional long form: Kingdom of Spain conventional short form: Spain local long form: Reino de Espana local short form: Espana |
| form | Spratly Islands | conventional long form: none conventional short form: Spratly Islands |
| form | Sri Lanka | conventional long form: Democratic 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 ... |
| form | Sudan | conventional long form: Republic of the Sudan conventional short form: Sudan local long form: Jumhuriyat as-Sudan local short form: As-Sudan former: Anglo-Egyptian Sudan |
| form | Suriname | conventional long form: Republic of Suriname conventional short form: Suriname local long form: Republiek Suriname local short form: Suriname former: Netherlands Guiana, Dutch Guiana |
| form | Svalbard | conventional long form: none conventional short form: Svalbard (sometimes referred to as Spitzbergen) |
| form | Swaziland | conventional long form: Kingdom of Swaziland conventional short form: Swaziland local long form: Umbuso weSwatini local short form: eSwatini |
| form | Sweden | conventional long form: Kingdom of Sweden conventional short form: Sweden local long form: Konungariket Sverige local short form: Sverige |
| form | Switzerland | conventional long form: Swiss Confederation conventional short form: Switzerland local long form: Schweizerische Eidgenossenschaft (German); Confederation Suisse (French); Confederazione Svizzera (Italian); Confederaziun Svizra (Romansh) local short form: Schweiz (German); Suisse (French); Svizzera ... |
| form | Syria | conventional long form: Syrian Arab Republic conventional short form: Syria local long form: Al Jumhuriyah al Arabiyah as Suriyah local short form: Suriyah former: United Arab Republic (with Egypt) |
| form | Taiwan | conventional long form: none conventional short form: Taiwan local long form: none local short form: T'ai-wan former: Formosa |
| form | Tajikistan | conventional long form: Republic of Tajikistan conventional short form: Tajikistan local long form: Jumhurii Tojikiston local short form: Tojikiston former: Tajik Soviet Socialist Republic |
| form | Tanzania | conventional long form: United Republic of Tanzania conventional short form: Tanzania local long form: Jamhuri ya Muungano wa Tanzania local short form: Tanzania former: United Republic of Tanganyika and Zanzibar |
| form | Thailand | conventional long form: Kingdom of Thailand conventional short form: Thailand local long form: Ratcha Anachak Thai local short form: Prathet Thai former: Siam |
| form | Timor-Leste | conventional long form: Democratic Republic of Timor-Leste conventional short form: Timor-Leste local long form: Republika Demokratika Timor Lorosa'e [Tetum]; Republica Democratica de Timor-Leste [Portuguese] local short form: Timor ... |
| form | Togo | conventional long form: Togolese Republic conventional short form: Togo local long form: Republique Togolaise local short form: none former: French Togoland |
| form | Tokelau | conventional long form: none conventional short form: Tokelau |
| form | Tonga | conventional long form: Kingdom of Tonga conventional short form: Tonga local long form: Pule'anga Tonga local short form: Tonga former: Friendly Islands |