Ekskalibur, Mač u Kamenu

Excalibur (/ɛkˈskælɪbər/), or Caliburn, is the legendary sword of King Arthur, sometimes also attributed with magical powers or associated with the rightful sovereignty of Britain. Excalibur and the Sword in the Stone (the proof of Arthur's lineage) are sometimes said to be the same weapon, but in most versions they are considered separate. Excalibur was associated with the Arthurian legend very early on. In Welsh, it is called Caledfwlch; in Cornish, Calesvol; in Breton, Kaledvoulc'h; and in Latin, Caliburnus.

Forms and etymologies
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".[1] Caledfwlch appears in several early Welsh works, including the prose tale Culhwch and Olwen. The name was later used in Welsh adaptations of foreign material such as the Bruts (chronicles), which were based on Geoffrey of Monmouth. 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. Simon Evans. They suggest instead that both names "may have similarly arisen at a very early date as generic names for a sword"; this sword then became exclusively the property of Arthur in the British tradition.[1][2]

Geoffrey of Monmouth, in his Historia Regum Britanniae (The History of the Kings of Britain, c. 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 [χάλυψ] "steel"). Most Celticists consider Geoffrey's Caliburnus to be derivative of a lost Old Welsh text in which bwlch (Old Welsh bulc[h]) had not yet been lenited to fwlch (Middle Welsh vwlch or uwlch).[3][4][1] 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. 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.[5]

In Old French sources this then became Escalibor, Excalibor, and finally the familiar Excalibur. Geoffrey Gaimar, in his Old French L'Estoire des Engleis (1134-1140), mentions Arthur and his sword: "this Constantine was the nephew of Arthur, who had the sword Caliburc" ("Cil Costentin, li niès Artur, Ki out l'espée Caliburc").[6][7] In Wace's Roman de Brut (c. 1150-1155), an Old French translation and versification of Geoffrey's Historia, the sword is called Calabrum, Callibourc, Chalabrun, and Calabrun (with alternate spellings such as Chalabrum, Calibore, Callibor, Caliborne, Calliborc, and Escaliborc, found in various manuscripts of the Brut).[8]

In Chrétien de Troyes' late 12th-century Old French Perceval,