Splinter group

A schism (pronounced /ˈsɪzəm/ SIZ-əm, /ˈskɪzəm/ SKIZ-əm or, less commonly, /ˈʃɪzəm/ SHIZ-əm) is a division between people, usually belonging to an organization, movement, or religious denomination. The word is most frequently applied to a split in what had previously been a single religious body, such as the East–West Schism or the Great Western Schism. It is also used of a split within a non-religious organization or movement or, more broadly, of a separation between two or more people, be it brothers, friends, lovers, etc.

A schismatic is a person who creates or incites schism in an organization or who is a member of a splinter group. Schismatic as an adjective means pertaining to a schism or schisms, or to those ideas, policies, etc. that are thought to lead towards or promote schism.

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Wikipedia