Definition of King Arthur from the Oxford Advanced Learner's Dictionary

(5th or 6th century) a king of England who led the Britons in battles against the Saxons. There are many stories about King Arthur, e.g. that he pulled his sword Excalibur from a stone, and that he sat with his knights at a Round Table. Nobody knows if the stories are true, but they are very popular and have been used in poems, plays and films.