Tre- (place name element)
Tre- or tref- is a place name element of Celtic origin meaning "hamlet, farmstead, estate", etc. which survives mainly in Cornwall and Wales.
The Cornish place-name beginning Tre- may be compared to the Cornish place-name beginning Bod- and the place-name endings -worthy and -cot in Devon, and -ham and -tun / -ton throughout England.
In a study by Oliver Padel of surviving place names in South-west England starting with "Tre-", including cities, towns, villages, hamlets, and individual farms, he found that almost all were situated west of the River Tamar, the natural border between Cornwall and Devon, with just a small concentration on the north-east side in Devon, near the narrower, shallower source area of the River. Padel reached two possible explanations: either Tre- names were formed at a date later than the Anglo-Saxon settlement of Devon, or Tre- names existing in Devon were superseded by new names following the Anglo-Saxon settlement of Devon. He concluded that the striking boundary line was evidence of political and linguistic distinction at some time from the 8th to 11th centuries.