word | | Country name |
| conventional | 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 |
| conventional | Sao Tome and Principe | conventional long form: Democratic Republic of Sao Tome and Principe conventional short form: Sao Tome and Principe local long form: Republica Democratica de Sao Tome e Principe local short form: Sao Tome ... |
| conventional | Saudi Arabia | conventional long form: Kingdom of Saudi Arabia conventional short form: Saudi Arabia local long form: Al Mamlakah al Arabiyah as Suudiyah local short form: Al Arabiyah as Suudiyah |
| conventional | Senegal | conventional long form: Republic of Senegal conventional short form: Senegal local long form: Republique du Senegal local short form: Senegal former: Senegambia (along with The Gambia), Mali Federation |
| conventional | Serbia | conventional long form: Republic of Serbia conventional short form: Serbia local long form: Republika Srbija local short form: Srbija former: People's Republic of Serbia, Socialist Republic of Serbia |
| conventional | Seychelles | conventional long form: Republic of Seychelles conventional short form: Seychelles local long form: Republic of Seychelles local short form: Seychelles |
| conventional | Sierra Leone | conventional long form: Republic of Sierra Leone conventional short form: Sierra Leone local long form: Republic of Sierra Leone local short form: Sierra Leone |
| conventional | Singapore | conventional long form: Republic of Singapore conventional short form: Singapore local long form: Republic of Singapore local short form: Singapore |
| conventional | Slovakia | conventional long form: Slovak Republic conventional short form: Slovakia local long form: Slovenska Republika local short form: Slovensko |
| conventional | Slovenia | conventional long form: Republic of Slovenia conventional short form: Slovenia local long form: Republika Slovenija local short form: Slovenija former: People's Republic of Slovenia, Socialist Republic of Slovenia |