'Great Schism' definitions:

Definition of 'Great Schism'

noun

The period from 1378 to 1417 during which there were two papacies in the Roman Catholic Church, one in Rome and one in Avignon

From: GCIDE

Schism \Schism\, n. [OE. scisme, OF. cisme, scisme, F. schisme, L. schisma, Gr. schi`sma, fr. schi`zein to split; akin to L. scindere, Skr. chid, and prob. to E. shed, v.t. (which see); cf. Rescind, Schedule, Zest.] Division or separation; specifically (Eccl.), permanent division or separation in the Christian church; breach of unity among people of the same religious faith; the offense of seeking to produce division in a church without justifiable cause. [1913 Webster]
Set bounds to our passions by reason, to our errors by truth, and to our schisms by charity. --Eikon Basilike. [1913 Webster]
Greek schism (Eccl.), the separation of the Greek and Roman churches.
Great schism, or Western schism (Eccl.) a schism in the Roman church in the latter part of the 14th century, on account of rival claimants to the papal throne.
Schism act (Law), an act of the English Parliament requiring all teachers to conform to the Established Church, -- passed in 1714, repealed in 1719. [1913 Webster]