a member (or supporter) of the house of Lancaster
lang-kas'tri-an, adj. pertaining to the dukes or the royal house of Lancaster.--n. an adherent of the house of Lancaster, as against the Yorkists, in the Wars of the Roses (1455-85).
(Adherent) of family descended from John of Gaunt Duke of Lancaster, or of the Red-rose party fighting for it in Wars of the Roses.
(Also) of Lancashire or Lancaster, (n.) inhabitant of these.
