| Country | Country name |
| Tonga | conventional long form: Kingdom of Tonga conventional short form: Tonga local long form: Pule'anga Tonga local short form: Tonga former: Friendly Islands |
| Trinidad and Tobago | conventional long form: Republic of Trinidad and Tobago conventional short form: Trinidad and Tobago |
| Tunisia | conventional long form: Tunisian Republic conventional short form: Tunisia local long form: Al Jumhuriyah at Tunisiyah local short form: Tunis |
| Turkey | conventional long form: Republic of Turkey conventional short form: Turkey local long form: Turkiye Cumhuriyeti local short form: Turkiye |
| Turkmenistan | conventional long form: none conventional short form: Turkmenistan local long form: none local short form: Turkmenistan former: Turkmen Soviet Socialist Republic |
| Turks and Caicos Islands | conventional long form: none conventional short form: Turks and Caicos Islands abbreviation: TCI |
| Tuvalu | conventional long form: none conventional short form: Tuvalu local long form: none local short form: Tuvalu former: Ellice Islands note: "Tuvalu" means "group of eight," referring to the country's eight traditionally inhabited islands |
| Uganda | conventional long form: Republic of Uganda conventional short form: Uganda |
| Ukraine | conventional long form: none conventional short form: Ukraine local long form: none local short form: Ukrayina former: Ukrainian National Republic, Ukrainian State, Ukrainian Soviet Socialist Republic |
| United Arab Emirates | conventional long form: United Arab Emirates conventional short form: none local long form: Al Imarat al Arabiyah al Muttahidah local short form: none former: Trucial Oman, Trucial States abbreviation: UAE |
| United Kingdom | conventional long form: United Kingdom of Great Britain and Northern Ireland; note - Great Britain includes England, Scotland, and Wales conventional short form: United Kingdom abbreviation: UK |
| United States | conventional long form: United States of America conventional short form: United States abbreviation: US or USA |
| United States Pacific Island Wildlife Refuges | conventional long form: none conventional short form: Baker Island; Howland Island; Jarvis Island; Johnston Atoll; Kingman Reef; Midway Islands; Palmyra Atoll |
| Uruguay | conventional long form: Oriental Republic of Uruguay conventional short form: Uruguay local long form: Republica Oriental del Uruguay local short form: Uruguay former: Banda Oriental, Cisplatine Province |
| Uzbekistan | conventional long form: Republic of Uzbekistan conventional short form: Uzbekistan local long form: Ozbekiston Respublikasi local short form: Ozbekiston former: Uzbek Soviet Socialist Republic |
| Vanuatu | conventional long form: Republic of Vanuatu conventional short form: Vanuatu local long form: Ripablik blong Vanuatu local short form: Vanuatu former: New Hebrides |
| Venezuela | conventional long form: Bolivarian Republic of Venezuela conventional short form: Venezuela local long form: Republica Bolivariana de Venezuela local short form: Venezuela |
| Vietnam | conventional long form: Socialist Republic of Vietnam conventional short form: Vietnam local long form: Cong Hoa Xa Hoi Chu Nghia Viet Nam local short form: Viet Nam abbreviation: SRV |
| Virgin Islands | conventional long form: United States Virgin Islands conventional short form: Virgin Islands former: Danish West Indies abbreviation: USVI |
| Wake Island | conventional long form: none conventional short form: Wake Island |
| Wallis and Futuna | conventional long form: Territory of the Wallis and Futuna Islands conventional short form: Wallis and Futuna local long form: Territoire des Iles Wallis et Futuna local short form: Wallis et Futuna |
| West Bank | conventional long form: none conventional short form: West Bank |
| Western Sahara | conventional long form: none conventional short form: Western Sahara former: Spanish Sahara |
| World | void |
| Yemen | conventional long form: Republic of Yemen conventional short form: Yemen local 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] |
| Zambia | conventional long form: Republic of Zambia conventional short form: Zambia former: Northern Rhodesia |
| Zimbabwe | conventional long form: Republic of Zimbabwe conventional short form: Zimbabwe former: Southern Rhodesia, Rhodesia |