The Proto-Indo-European word *swordó-
Word *swordó-
Meaning black
Synonyms *kers-, *kʷr̥snós

Comments
Lat. sordēre, Eng. sweart/swarthy, Gm. swarz/schwarz, Goth. swarts, ON svartr, Lith. sartas

Other words that might be of interest
*temó- ‘dark’, *dh(o)ngu- ‘dark’, *(hₐ)mauros ‘dark’, *(hₐ)merhₓgʷ- ‘dark’, *tómhₓes- ‘dark’