Welsh pwy

← Breton piv (cognate)

← Proto-Brythonic *puɨ (inherited)

← Proto-Celtic *kʷēs (inherited)

← Proto-Indo-European *kʷis (inherited)

← Cornish piw (cognate)

← Old Welsh pui (inherited)

← Old Irish cía (cognate)

→ Breton piv (cognate)

→ Welsh piau (mention)

→ Irish cé (cognate)

→ Scottish Gaelic cò (cognate)

→ Cornish piw (cognate)

→ Middle Irish cía (cognate)

→ Old Irish cía (cognate)