Breton trec'h

← Proto-Brythonic *trex (inherited)

← Proto-Celtic *trexsos (inherited)

← Cornish trygh (cognate)

← Old Norse þróttr (cognate)

← Old Irish trén (cognate)

← Old Irish tressa (mention)

← Old Irish tressiu (mention)

← Middle Welsh trech (cognate)

→ Welsh trech (cognate)

→ Old Irish trén (cognate)