Breton erer

← Proto-Celtic *eriros (inherited)

← Welsh eryr (cognate)

← Proto-Indo-European *h₃érō (inherited)

← Cornish er (cognate)

← Old Irish *irar (cognate)

→ Breton erered (suffix)

→ Welsh eryr (cognate)

→ Irish iolar (cognate)

→ Scottish Gaelic iolair (cognate)

→ Manx urley (cognate)

→ Cornish er (cognate)

→ Middle Irish ilar (cognate)