Breton deiz

← Proto-Brythonic *dið (inherited)

← Proto-Celtic *dīyos (inherited)

← Welsh dydd (cognate)

← Proto-Indo-European *di̯ēus (inherited)

← Proto-Indo-European *dyew- (mention)

← Cornish dydh (cognate)

← Latin diēs (cognate)

← Old Irish día (cognate)

→ Breton bemdez (mention)

→ Breton deizioù (affix)

→ Breton devezh (suffix)

→ Breton deiziadur (affix)

→ Welsh dydd (cognate)

→ Cornish dedh (cognate)