

In Old French sources this then became Escalibor, Excalibor, and finally the familiar Excalibur.

It is unclear if the name was borrowed from the Welsh (if so, it must have been an early loan, for phonological reasons), or represents an early, pan-Brittonic traditional name for Arthur's sword. In the late 15th/early 16th-century Middle Cornish play Beunans Ke, Arthur's sword is called Calesvol, which is etymologically an exact Middle Cornish cognate of the Welsh Caledfwlch. Most Celticists consider Geoffrey's Caliburnus to be derivative of a lost Old Welsh text in which bwlch (Old Welsh bulc) had not yet been lenited to fwlch ( Middle Welsh vwlch or uwlch). 1136), Latinised the name of Arthur's sword as Caliburnus (potentially influenced by the Medieval Latin spelling calibs of Classical Latin chalybs, from Greek chályps "steel"). Geoffrey of Monmouth, in his Historia Regum Britanniae ( The History of the Kings of Britain, c. This sword then became exclusively the property of Arthur in the British tradition.

They suggest instead that both names "may have similarly arisen at a very early date as generic names for a sword". It is often considered to be related to the phonetically similar Caladbolg, a sword borne by several figures from Irish mythology, although a borrowing of Caledfwlch from Irish Caladbolg has been considered unlikely by Rachel Bromwich and D. The name was later used in Welsh adaptations of foreign material such as the Bruts (chronicles), which were based on Geoffrey of Monmouth. Caledfwlch appears in several early Welsh works, including the prose tale Culhwch and Olwen (c. The name Excalibur ultimately derives from the Welsh Caledfwlch (and Breton Kaledvoulc'h, Middle Cornish Calesvol), which is a compound of caled "hard" and bwlch "breach, cleft". 2 The sword in the stone and the sword in the lake.
