Breton dour

← Proto-Brythonic *duβr (inherited)

← Proto-Celtic *dubros (inherited)

← Proto-Indo-European *dʰewbʰ- (root)

← Proto-Indo-European *dʰubʰrós (inherited)

→ Breton dourek (suffix)

→ Breton douryar (compound)

→ Breton dourgi (compound)

→ Breton dourgon (affix)

→ Breton dourioù (suffix)

→ Breton douryer (affix)

→ Welsh dŵr (cognate)

→ German Tauber (cognate)