Somalia
noun: Somali(s)
adjective: Somali
South Africa
noun: South African(s)
adjective: South African
Spain
noun: Spaniard(s)
adjective: Spanish
Sri Lanka
noun: Sri Lankan(s)
adjective: Sri Lankan
Sudan
noun: Sudanese (singular and plural)
adjective: Sudanese
Suriname
noun: Surinamer(s)
adjective: Surinamese
Swaziland
noun: Swazi(s)
adjective: Swazi
Sweden
noun: Swede(s)
adjective: Swedish
Switzerland
noun: Swiss (singular and plural)
adjective: Swiss
Syria
noun: Syrian(s)
adjective: Syrian