Where does “blā” come from?

blā (Proto-Celtic) comes from Proto-Indo-European bʰel-, from Proto-Indo-European bʰōl-.

Ancestry of “blā”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	bʰel-	to sound; to speak, roar, bark; shiny, white; to...
2	Proto-Indo-European	bʰōl-	—