Breton buoc'h

← Proto-Brythonic *bʉx (inherited)

← Proto-Celtic *boukkā (inherited)

← Proto-Celtic *bāus (mention)

← Welsh buwch (cognate)

← Irish bó (cognate)

← Manx booa (cognate)

← Proto-Indo-European *gʷṓws (derived)

← Cornish bugh (cognate)

→ Cornish bugh (cognate)

→ Cornish buwgh (cognate)