by Brian Edward Rise

The name of Arthur's sword in Geoffrey of Monmouth. Later modified by the romancers into Excalibur. Geoffrey says the sword was forged in the Isle of Avalon, here meaning most decidedly a mystic place in the Otherworld rather than Glastonbury. In Geoffrey, Arthur wields Caliburn when he defeats the Saxons at Bath, in single combat with Roman governor Frollo outside Paris, and in his battle with the Roman army commanded by Lucius. The sight of Caliburn spurred the troops onward and the enemy's armor gave them no protection from its power.

The name was probably suggested by the Latin word, chalybs, which meant "steel" and could be used metaphorically for a sword. There may also be a trace of the Welsh name given to Arthur's sword in Culhwch ac Olwen — Caledfwlch, which also resembles Caladbolg, the famous sword of Irish legend.