English Place-name Society

Survey of English Place-Names

A county-by-county guide to the linguistic origins of England’s place-names – a project of the English Place-Name Society, founded 1923.


Early-attested site in the Parish of North Petherwin

Historical Forms

  • Casteswurth 1228 FF
  • Catteswurthi 1249 Ass
  • Castesworthy 1270 Ass
  • Keastesworthi 1330 SR
  • Carsworthy 1551 DeedsEnrolled 1612 Recov
  • Kersworthy al. Kearsworthy al. Catisworthy 1762 Recov


v. worþig . For the first element we may compare Keason (Co), Kestingtun c. 1150 (1348) Pat, Keyston 1571FF , and Lankeast (Co), Lankest 1364Ass , 1380 FF. Loth (Chrest. 19) notes Cast as the name of a Breton saint, possibly derived from the Lat castus . There seems to be no evidence that this was used as an ordinary pers. name in British, but it may possibly be connected with the Cornish surname Keast .