The term 'ecclesiastical split' is a synonym for the word 'SCHISM, ' which is defined as a division or separation within a religious body. This term is often used to describe a formal break in the unity of a church or other religious organization, usually caused by doctrinal disagreements or power struggles. The most famous example of an ecclesiastical split is the Great SCHISM of 1054, which divided the Christian Church into the Roman Catholic and Eastern Orthodox branches.