Welsh wyth

← Proto-Brythonic *üiθ (inherited)

← Proto-Celtic *oxtū (inherited)

← Proto-Indo-European *oḱtṓw (inherited)

← Cornish eth (cognate)

→ Welsh wythnos (compound)

→ Welsh wythfed (affix)

→ Welsh wythongl (compound)

→ Welsh wyth ar hugain (compound)

→ Welsh un deg wyth (compound)

→ Welsh dau ddeg wyth (compound)

→ Cornish eth (cognate)