word | | Country name |
| iya | Ethiopia | conventional long form: Federal Democratic Republic of Ethiopia conventional short form: Ethiopia local long form: Ityop'iya Federalawi Demokrasiyawi Ripeblik local short form: Ityop'iya former: Abyssinia, Italian East Africa abbreviation: FDRE |
| Jamaica | Jamaica | conventional long form: none conventional short form: Jamaica |
| Jamhuri | Kenya | conventional long form: Republic of Kenya conventional short form: Kenya local long form: Republic of Kenya/Jamhuri ya Kenya local short form: Kenya former: British East Africa |
| Jamhuri | 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 |
| Jamhuryat | Pakistan | conventional long form: Islamic Republic of Pakistan conventional short form: Pakistan local long form: Jamhuryat Islami Pakistan local short form: Pakistan former: West Pakistan |
| Jamhuuriyada | Somalia | conventional long form: none conventional short form: Somalia local long form: Jamhuuriyada Demuqraadiga Soomaaliyeed local short form: Soomaaliya former: Somali Republic, Somali Democratic Republic |
| Jan | Jan Mayen | conventional long form: none conventional short form: Jan Mayen |
| Jananayaka | 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 |
| Janarajaya | 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 |
| Japan | Japan | conventional long form: none conventional short form: Japan local long form: Nihon-koku/Nippon-koku local short form: Nihon/Nippon |
| Jarvis | 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 |