Where does “*bowitrom” come from?

*bowitrom (Celtic) comes from Proto-Indo-European h₁itós, from Proto-Indo-European h₁éy- — he, this.

Ancestry of “*bowitrom”, step by step

StepLanguageWordMeaning
1Proto-Indo-Europeanh₁itóspassable
2Proto-Indo-Europeanh₁éy-he, this
Every word from Proto-Indo-European h₁éy- →Every word from Proto-Indo-European h₁itós →