This word popped up in a book of short stories I’ve just finished reading:
So, the land there is thickly forested to the north and the forest grows even more thickly and densely to the south. This southern cantrev of forest is so very dense, indeed, that there is no other place in the world with trees of such height or magnificence or profusion.
Adam Robots, by Adam Roberts, 2013.
A cantrev — the word has been spelled in numerous ways, including cantref and canthrif — turns out upon enquiry to have been a medieval legal division of Wales (from the Welsh cant, a hundred, plus tref, a town or place). It’s closely similar in sense to the English hundred, a division of a county or shire for administrative purposes. In fact, in medieval England yet another form of the word, cantred, was used almost synonymously with hundred.
The word has long had only historical interest. But it has enjoyed a minor revival in SF and fantasy — as in Lloyd Alexander’s Prydain Chronicles — as an unfamiliar term with which to communicate a quality of being different or elsewhere. The revival is most probably due to modern interest in the medieval Welsh epic The Mabinogion, in which cantrev often appears.