The word schism ('sɪzəm or /'skɪzəm/), from the Greek σχίσμα, skhísma (from σχίζω, skhízō, "to tear, to split"), means a division or a split, usually in an organization or a movement.
A schismatic is a person who creates schism in an organization or who is a member of a splinter group. Schismatic as an adjective means belonging to a schism or schisms, or to those ideas, policies, etc. that are thought to lead towards schism.

The words schism and schismatic have found perhaps their heaviest usage in the history of Christianity, to speak of splits within a church.
Within Christianity the word schism might mean:
Different denominations of Christianity have different beliefs on schism. For example, commiting an act of heresy within the Catholic Church brings the punishment of excommunication.
There are divisions between Sunni, Shia, and Kharijite Islam in CE 632 regarding the rightful successor to the prophet Muhammad. In 661 and 680 there were divisions regarding the rightful claimant to the Caliphate.

In Buddhism, the first schism was set up by Devadatta, during Buddha's life. After Buddha's passing away, the early Buddhist schools developed various schisms. In the old texts, 18 or 20 early schools are mentioned. Later, there were the Mahayana and Vajrayana movements, which can be regarded as being schismatic in origin. There are now perhaps thousands of different Buddhist sects.
The first schism in Jainism happened around the fourth century BCE, leading to rise of two major sects, Digambara and Svetambara, which were later subdivided in further sub-sects.
Throughout the Jewish history, Judaism survived many schisms. Today, major Jewish denominations are Orthodox Judaism and non-Orthodox: Reform, Conservative and Reconstructionist.