Welsh nerth

← Breton nerzh (cognate)

← Proto-Brythonic *nerθ (inherited)

← Proto-Celtic *nertom (inherited)

← Irish neart (cognate)

← Proto-Indo-European (inherited)

← Proto-Indo-European *h₂nḗr (mention)

← Cornish nerth (cognate)

→ Breton nerzh (cognate)

→ Irish neart (cognate)

→ Cornish nerth (cognate)