Cathar
Concise Oxford English Dictionary © 2008 Oxford University Press:
Cathar /ˈkaθɑː/
▶noun (pl. Cathars or Cathari /-ri/) a member of a heretical medieval Christian sect which sought to achieve great spiritual purity.
– derivatives
Catharism noun,
Catharist noun & adjective.
Catharism noun,
Catharist noun & adjective.
– origin C17: from med. L. Cathari (pl.), from Gk katharoi ‘the pure’.
'Cathar' also found in these Oxford entries:

