Definition of "Pendragon"

It befell in the days of Uther Pendragon, when he was king of all England, and so reigned, that there was a mighty duke in Cornwall that held war against him long time.

1485, Thomas Malory, chapter 1, in Le Morte D'Arthur‎, book I

At last he got his breath and answer'd, 'One, / One have I seen—that other, our liege lord, / The dread Pendragon, Britain's king of kings, / Of whom the people talk mysteriously, / He will be there—then were I stricken blind / That minute, I might say that I have seen.'

1859, Alfred Tennyson, “Elaine”, in Idylls of the King, London: Edward Moxon & Co., […], page 169

[I]n the reign of Henry the Second, a body happening, by chance, to be dug up near Glastonbury Abbey, without any symptoms of putrefaction or decay, the Welch, the descendants of the Ancient Britons, tenacious of the dignity and reputation of that illustrious hero [King Arthur], vainly supposed it could be no other than the body of their justly-boasted Pen-Dragon; and that he had been immured in that sepulchre by the spells of some powerful and implacable inchanter.

1810, J[ohn] Stagg, “Arthur’s Cave. A Legendary Tale.”, in The Minstrel of the North: Or, Cumbrian Legends. […], London: Printed by Hamblin and Seyfang, […], for the author, and sold by J. Blacklock, […], page 105

At last he got his breath and answer'd, 'One, / One have I seen—that other, our liege lord, / The dread Pendragon, Britain's king of kings, / Of whom the people talk mysteriously, / He will be there—then were I stricken blind / That minute, I might say that I have seen.'

1859, Alfred Tennyson, “Elaine”, in Idylls of the King, London: Edward Moxon & Co., […], page 169

To recap, with a view to understanding the 'Uther' in 'Utherpendragon', Emrys, the first Pen Dragon, fought the Angles in the 550s. Gwenddolau, the second Pen Dragon, fought the Angles in the 560s and early 570s. Maelgwn became Pen Dragon after Arderydd in 573, although by then there was no organised force for him to take over. As there were only two Pen Dragons of moment, it would have been natural for people living hundreds of years later to refer to Emrys as Pen Dragon and Gwenddolau as the other Pen Dragon.

2007, Adam Ardrey, “Uther Pendragon, Son of the Sky God”, in Finding Merlin: The Truth behind the Legend, Edinburgh: Mainstream Publishing