Welsh pedwerydd

← Proto-Brythonic *pėdwėrɨð (inherited)

← Proto-Celtic *kʷetwariyos (inherited)

← Welsh pedwar (affix)

← Welsh -ydd (affix)

→ English methera (mention)

→ Welsh pedwerydd ar ddeg (compound)

→ Welsh pedwerydd ar bymtheg (compound)

→ Welsh pedwerydd ar hugain (compound)

→ Welsh pedwerydd ar bymtheg a phedwar ugain (compound)