Where does “beinn” come from?

beinn (Irish) comes from Irish bí, from Old Irish bí, from Proto-Celtic bitu, from Proto-Indo-European bʰeyh₂- — to fear, be afraid; to strike, hit; to hew, cut.

beinn (Irish): first-person singular past subjunctive of bí

Definitions

first-person singular past subjunctive of bí

Ancestry of “beinn”, step by step

Step	Language	Word	Meaning
1	Irish	bí	be; pitch, resin; genitive singular masculine of...
2	Old Irish	bí	second/third-person singular habitual present...
3	Proto-Celtic	bitu	—
4	Proto-Indo-European	bʰeyh₂-	to fear, be afraid; to strike, hit; to hew, cut

Every word from Proto-Indo-European bʰeyh₂- →Every word from Proto-Celtic bitu →Every word from Old Irish bí →