Welsh eryr

← Breton erer (cognate)

← Proto-Celtic *eriros (inherited)

← Proto-Indo-European *h₃érō (derived)

← Cornish er (cognate)

← Old Irish *irar (cognate)

→ Breton erer (cognate)

→ Irish iolar (cognate)

→ Scottish Gaelic iolair (cognate)

→ Manx urley (cognate)

→ Cornish er (cognate)

→ Middle Irish ilar (cognate)