takfir /täkˈfir, tɑkˈfɪr 
/ ▸ noun the action or practice of declaring that a fellow Muslim is guilty of apostasy (i.e. not believing in the essential tenets of Islam) and therefore no longer a Muslim.
– ORIGIN Arabic takfīr, verbal noun of kaffara ‘call someone an apostate’.
EnglishOxford New American Dictionary
