Sanja means “dream” in Serbian and Croatian.
Senka means “shadow” in Serbian and Croatian. The male form is Senko.
Simonida is the Serbian feminine form of the Greek name Simonides (son of the flat-nosed one). I have a character by this name. This was also the name of King Milutin’s fourth wife. At age five, she was married to the almost-50-year-old King Milutin, who had adult kids. Some sources say Milutin consummated the marriage (i.e., raped Simonida) before she was an adult, causing permanent uterine damage and infertility. After her husband’s death, she realised her longtime dream of becoming a nun.
Sirma means “golden thread” or “silver thread” in Bulgarian.
Snezhana (Russian, Bulgarian, Macedonian), Snyazhana (Belarusian), Snežana (Serbian), Snježana (Serbian, Croatian), Snizhana (Ukrainian) means “snowy.”
Stoyanka (Bulgarian), Stoja (Croatian) means “to stay, to stand.” The male forms are Stoyan (Bulgarian) and Stojan (Macedonian, Serbian, Slovenian, Croatian).
Sambor means “to fight alone” or “alone in battle” in Polish.
Savva (Russian), Sava (Bulgarian, Serbian) derives from the Greek name Sabas, and ultimately from the Hebrew word sava (old man). Serbia’s patron saint is named Sava. Many Serbian churches bear his name.
Sieciech roughly means “he who enjoys the universe” in Polish.
Spartak is the Russian, Bulgarian, Ukrainian, Armenian, Georgian, and Albanian form of the Latin name Spatacus (from Sparta).
Sulirad means “better care” or “to promise care” in Polish.
Svyatopolk is a rare Russian name meaning “blessed people.” This was the name of two grand princes of Kyivan Rus, part of the Ryurikovich Dynasty.