Cathar /ˈkæθɑɹ/ noun1 •A member of certain so self-styled Novatian and other medieval Christian sects embracing a form of dualism and extraordinary practices purportedly adhering to Mary Magdalene's teachings, persecuted by Roman Catholics as heretics.The Albigenses, famous Cathars in and around Albi (southern France), were eradicated in a bloody ‘crusade’. formsCathari · Cathars