Takfiri

A takfiri (Arabic:تكفيري‎ takfīrī) is a Sunni Muslim who accuses another Muslim (or an adherent of another Abrahamic faith) of apostasy. The accusation itself is called takfir, derived from the word kafir (unbeliever), and is described as when "one who is, or claims to be, a Muslim is declared impure." Accusing other Muslims of being takfiris has become a sectarian slur, particularly since the outbreak of the Syrian Civil War in 2011.