From Proto-Indo-European*s(h₂)wél-jo- 'sun', from the oblique stem of *sóh₂wl̥. For the development of the initial compare djersë(“sweat”) from *sweyd-, and dergjem(“lie ill”) from mediopassive Proto-Indo-European*sworgʰ-eje- from *swergʰ(“watch over, worry”).