Lancastrian /lænˈkæstɹɪ.ən/noun 3adjective 2forms 3 noun3 •A person from Lancaster or Lancashire. •(historical) An adherent of the house of Lancaster, as against the Yorkists, in the Wars of the Roses. •(historical) A modified version of the Lancaster bomber, used in civilian service in the immediate postwar years. adjective2 •Of or relating to Lancaster or Lancashire. •Relating to the dukes or the royal house of Lancaster. formsLancastrians · more Lancastrian · most Lancastrian