Arabic: qadāsa 'al-bābā
"Pope" denotes the highest cleric of the Roman Catholic Church and the Coptic Church.
It comes from Greek pappas, simply meaning "father". In Latin it is papa.
The use of "pope" was during early Christian history used as an expression of affectionate respect, bestowed upon bishops and sometimes even priests.
When used for the Pope in Rome it is in reality a popular title, as the Pope's official titles is in a list of 8 titles bestowed upon his office, beginning with Bishop of Rome, Vicar of Jesus Christ. "Pope" is not mentioned in this list at all.
The Roman Catholic Church defines the Pope as the successor of St. Peter, the head of the apostles. The Pope in Rome achieved his primacy with by Rome remaining the most important city during the decisive 4th and 5th centuries, when many of the tenants of Christianity were defined. Over the centuries that followed, the Pope in Rome managed to remain the single most influential institution in the Christian world, although rivalled by the Patriarch of Constantinople.
The Pope in Rome has full and supreme power of jurisdiction over the universal church in matters of faith and morals, as well as in church discipline and government. The Pope and Patriarch in Alexandria
In the Coptic Church, the title is Pope and Patriarch of Alexandria, Pentapolis and Ethiopia. His position is as influential for his own church as the Pope in Rome's, but it is only the Pope in Rome who exercises great influence over all of Christianity.
Priests and bishops of the Orthodox churches can still be affectionately referred to as Pope.
The term is occasionally used for non-Christian groups too.