| Country | Country name |
| Sweden | conventional long form: Kingdom of Sweden conventional short form: Sweden local long form: Konungariket Sverige local short form: Sverige |
| 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 (Italian); Svizra (Romansh) |
| 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) |
| Taiwan | conventional long form: none conventional short form: Taiwan local long form: none local short form: Taiwan former: Formosa |
| 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 |
| 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 |
| Thailand | conventional long form: Kingdom of Thailand conventional short form: Thailand local long form: Ratcha Anachak Thai local short form: Prathet Thai former: Siam |
| Timor-Leste | conventional long form: Democratic Republic of Timor-Leste (pronounced TEE-mor LESS-tay) conventional short form: Timor-Leste local long form: Republika Demokratika Timor Lorosa'e [Tetum]; Republica Democratica de Timor-Leste [Portuguese] local short form: Timor Lorosa'e [Tetum]; Timor-Leste [Portuguese] former: East Timor, Portuguese Timor |
| Togo | conventional long form: Togolese Republic conventional short form: Togo local long form: Republique togolaise local short form: none former: French Togoland |
| Tokelau | conventional long form: none conventional short form: Tokelau |
| Tonga | conventional long form: Kingdom of Tonga conventional short form: Tonga local long form: Pule'anga Tonga local short form: Tonga former: Friendly Islands |