Where does “suncostaj” come from?
suncostaj (Serbo-Croatian) comes from Serbo-Croatian sȗnce, from Proto-Slavic sъlnьce, from Proto-Balto-Slavic *súlˀnis, from Proto-Indo-European sóh₂wl̥ — sun.
suncostaj (Serbo-Croatian): solstice
Ancestry of “suncostaj”, step by step