town in Somersetshire, famous as a prehistoric site, Old English Glestingabyrig, Glastingburi (725), "Stronghold (Old English byrig, dative of burh) of the people (Old English -inga-) living at Glaston," a Celtic name, possibly meaning "woad place."

legendary castle of King Arthur, a name first found in medieval French romances; the name corresponds to Latin Camuladonum, the Roman forerunner of Colchester, which was an impressive ruin in the Middle Ages. But Malory identifies it with Winchester and Elizabethans tended to see it as Cadbury Castle, an Iron Age hill fort near Glastonbury.