The Proto-Celtic word *aidu
Word *aidu
Meaning fire
See also Avestan: ātar- ‘fire’
Synonyms *taφnos-, *angelo-

Other words that might be of interest
*sūl- ‘sun’, *dumāko- ‘mist’, *dengwo ‘smoke, mist’, *mūko- ‘smoke’, *dwijat ‘smoke’, *onno ‘ash’, *loutwi ‘ashes’, *dubu ‘dark, black’, *skalī- ‘shadow’