Caliburn was the original name of the famous sword Excalibur. In Welsh legend, Arthur's sword is known as Caledfwlch.
Geoffrey of Monmouth's History of the Kings of Britain is the first non-Welsh source to speak of the sword. Geoffrey says the sword was forged in Avalon and Latinises the name "Caledfwlch" as Caliburnus. When his influential pseudo-history made it to Continental Europe, writers altered the name further until it finally took on the popular form Excalibur (various spellings in the medieval Arthurian Romance and Chronicle tradition include: Calabrun, Calabrum, Calibourne, Callibourc, Calliborc, Calibourch, Escaliborc, and Escalibor.
Caliburn is also the name of one of the domains in Kingdoms of Camelot.