Where does “b” come from?

b (Middle Irish) comes from Old Irish odb, from Proto-Celtic odbos, from Proto-Indo-European h₃ésth₁ — bone.

Ancestry of “b”, step by step

StepLanguageWordMeaning
1Old Irishodbknot; lump, swelling, protuberance; difficulty,...
2Proto-Celticodbosknot, bulge
3Proto-Indo-Europeanh₃ésth₁bone
Every word from Proto-Indo-European h₃ésth₁ →Every word from Proto-Celtic odbos →Every word from Old Irish odb →