schism
Concise Oxford English Dictionary © 2008 Oxford University Press:
schism /ˈsɪz(ə)m, ˈskɪz(ə)m/
▶noun
- 1 a division between strongly opposed parties, caused by differences in opinion or belief.
- 2 the formal separation of a Church into two Churches or the secession of a group owing to doctrinal and other differences.
– origin ME: from OFr. scisme, via eccles. L. from Gk skhisma ‘cleft’, from skhizein ‘to split’.
'schism' also found in these Oxford entries:

