Welsh tew

← Proto-Brythonic *teɣ (inherited)

← Proto-Celtic *tegus (inherited)

← Proto-Indo-European *tégus (inherited)

→ English thick (cognate)

→ Breton tev (cognate)

→ Welsh tewach (suffix)

→ Welsh tewaf (suffix)

→ Welsh bochdew (compound)

→ Welsh cytew (compound)

→ Old Irish tiug (cognate)

→ Albanian thuk (cognate)