Senegal
noun: Senegalese (singular and plural)
adjective: Senegalese

Serbia and Montenegro
noun: Serb(s); Montenegrin(s)
adjective: Serbian; Montenegrin

Seychelles
noun: Seychellois (singular and plural)
adjective: Seychellois

Sierra Leone
noun: Sierra Leonean(s)
adjective: Sierra Leonean

Singapore
noun: Singaporean(s)
adjective: Singapore

Slovakia
noun: Slovak(s)
adjective: Slovak

Slovenia
noun: Slovene(s)
adjective: Slovenian

Solomon Islands
noun: Solomon Islander(s)
adjective: Solomon Islander

Somalia
noun: Somali(s)
adjective: Somali

South Africa
noun: South African(s)
adjective: South African