it derives from purportedly poetic words meaning "lost land", and was originally applied to areas of Mercia after the Saxon conquest before being applied to the whole of England. Many English county towns, founded as Roman castra and now having the English suffix "-c(h)ester", also have Welsh names, in most cases using the prefix Caer-. Examples include Caer or Caerlleon (for Chester), Caerloyw (Gloucester), Caerwrangon (Worcester), Caergrawnt (Cambridge, from Grantchester), and Caerwynt (Winchester). In some other cases, Welsh names are translations of the English name, often influenced by the Welsh poetic tradition – for example, Rhydychen (literally, "oxen ford") for Oxford, and Gwlad-yr-haf ("land of summer") for Somerset. There are some erroneous "translations" such as Rhydwely for Bedford, which is actually derived from an English personal name Beda, and not the noun "bed" (Welsh (g)wely). Some English cities which have developed more recently, but with which Welsh people have had commercial links through trading or other economic associations such as through population migration, have developed Welsh forms of their English names. Examples are Bryste (Bristol) and Lerpwl (Liverpool), although some claim that Liverpool has a possible Welsh derivation from "Y Llif", a name for the Atlantic Ocean and meaning "the flood" together with "pwll" which represents the word Pool in English place names and is generally accepted as of Brythonic origin.. However such a name is impossible in Welsh, and would certainly could not have given "Liverpool", whose origin is clearly Old English A final set of Welsh place-names are those for settlements in England which lie close to the modern border with Wales. In some cases, such as Ross-on-Wye (Rhosan-ar-Wy) and probably Leominster (Llanllieni), the English name seems to have derived from the Welsh name. In other cases, such as Llwydlo (Ludlow) and Henffordd (Hereford), the Welsh name derived from the English name of the settlement. The Welsh name for Shrewsbury, Yr Amwythig, means "the fort in scrubland", which is one theory of the origin of the English name. Oswestry ("Oswald's tree") is in Welsh Croesoswallt ("Oswald's cross") – although Old English treow in fact meant "cross" as well as "tree". See also Aber and Inver as place-name elements Celtic onomastics Celtic toponymy Cumbrian toponymy Irish toponymy List of generic forms in place names in the United Kingdom and Ireland Llan place name element Scottish toponymy Toponymy in Great Britain Welsh Place-Name Society Welsh place names in other countries