What is "dunmail"

Dunmail is a legendary king of Cumberland associated with Dunmail Raise. According to tradition, Dunmail was the last king of Cumberland, and buried beneath the cairn at Dunmail Raise after having been slain by the English. Dunmail Raise, meaning "Dyfnwal's Cairn", may well be named after the historical Dyfnwal ab Owain, King of the Cumbrians.