the English royal family that reigned 1399–1461, descended from John of Gaunt (Duke of Lancaster), and that included Henry IV, Henry V, and Henry VI. Compare York(def. 1).
the English royal house that reigned from 1399 to 1461
Lancaster1 (ˈlæŋkəstə)
—n
a city in NW England, former county town of Lancashire, on the River Lune: castle (built on the site of a Roman camp); university (1964). Pop: 45 952 (2001)
Loncastre (1086) "Roman Fort on the River Lune," a Celtic river name probably meaning "healthy, pure." The Lancastrians in the War of the Roses took their name from their descent from John of Gaunt, Duke of Lancaster.