The Proto-Celtic word *sūl-
Word *sūl-
Meaning sun

Other words that might be of interest
*loukno- ‘moon’, *ster ‘star’, *moudo ‘cloud’, *kewok- ‘fog’, *dumāko- ‘mist’, *dengwo ‘smoke, mist’, *mūko- ‘smoke’, *dwijat ‘smoke’, *taφnos- ‘fire’, *aidu ‘fire’, *angelo- ‘fire, light’, *onno ‘ash’, *loutwi ‘ashes’, *dubu ‘dark, black’, *skalī- ‘shadow’