Welsh byd

← Proto-Brythonic *bɨd (inherited)

← Proto-Celtic *bitus (inherited)

← Welsh byth (doublet)

→ Breton bed (cognate)

→ Welsh byth (doublet)

→ Welsh byd-eang (affix)

→ Welsh bydwraig (compound)

→ Welsh isfyd (compound)

→ Welsh adfyd (affix)

→ Irish bith (cognate)

→ Old Irish bith (cognate)