Catholicos of the East explained

Catholicos of the East is the title that has been held by the ecclesiastical heads of the Church of the East, the Grand Metropolitan of Seleucia-Ctesiphon, since AD. 280.

The term "Catholicos" is derived from the Greek word Katholikos (Καθολικός), meaning "Universal Bishop". The title Catholicos, is used in several Eastern Christian churches and implies a degree of sovereignty and autocephaly.

Catholicos of the East refers to:

• Catholicos-Patriarch of the East, primate (Catholicos-Patriarch) of the Church of the East.

It may also refer to the ecclesiastical heads of the different branches of the Church of the East

• Catholicos-Patriarch of the Assyrian Church of the East
• Catholicos-Patriarchs of the Ancient Church of the East
• Chaldean Catholic Patriarchs of Babylon

Catholicos of the East also refers to some ecclesiastical institutions of later origin:

• Syriac Maphrian of the East^[1]
• Catholicos of the East and Malankara Metropolitan, the primate of Malankara Orthodox Syrian Church.^[2] The Catholicos position came into existence in the Church in 1912 with the establishment of the Catholicate. From 1934, the Catholicos began to hold the position of Malankara Metropolitan also, another important title in the Church.
• Catholicos of India, the head of the Jacobite Syrian Christian Church,^[3] whose historic titles are Catholicos of the East and Metropolitan of Malankara.^{[4] [5]}

Sources

• Book: Burleson. Samuel. Rompay. Lucas van. List of Patriarchs of the Main Syriac Churches in the Middle East. Gorgias Encyclopedic Dictionary of the Syriac Heritage. 2011. Piscataway, NJ. Gorgias Press. 481–491. https://gedsh.bethmardutho.org/List-of-Patriarchs-Churches-Middle-East.
• Book: Walker, Williston. Williston Walker. A History of the Christian Church. 1985. 1918. New York. Scribner. 9780684184173.
• Book: Wilmshurst, David. The Ecclesiastical Organisation of the Church of the East, 1318–1913. 2000. Louvain. Peeters Publishers. 9789042908765.
• Book: Wilmshurst, David. The Patriarchs of the Church of the East. The Syriac World. 2019. London. Routledge. 799–805. 9781138899018. https://books.google.com/books?id=E48JswEACAAJ.
• Book: Wilmshurst, David. The martyred Church: A History of the Church of the East. 2011. London. East & West Publishing Limited. 9781907318047.

Notes and References

1. Web site: Patriarch Zakka I: The SOC At a Glance. 2022-04-24. syriacorthodoxresources.org. "During the third century, a number of bishoprics were gradually organized and a general leadership was established, with Madaen as its center, in the ecclesiastical region under the jurisdiction of the Apostolic See of Antioch. Its bishop was called Bishop of the East, or Catholicos of the East, and was later known as the Maphryono of the East.".
2. Web site: H.H. Baselios Marthoma Mathews III, The Ninth Catholicos of the East in Malankara . 2022-04-24. mosc.in. "His Holiness Baselios Marthoma Mathews III was enthroned as the Catholicos of the East & Malankara Metropolitan (the Supreme Head of the Malankara Orthodox Syrian Church of India) on Friday, 15th October 2021".
3. Web site: Jacobite Syrian Christian Church . https://archive.today/20150610064111/http://www.jscnews.org/pages/page.php?content_id=33 . usurped . June 10, 2015 . JSC News- Official News Portal of the Church. 2022-04-24. "In the Malankara Jacobite Syrian Orthodox Church, the Patriarch of Antioch & all the East is the spiritual supreme, but the temporal powers of the local Church in India rests with an association, elected from among the representatives of Parishes of Malankara, and is to be administered under guidance from its Chief prelate, the Catholicos of India.".
4. Book: Constitution. Syriac Orthodox Church Constitution. 1998. His Beatitude The Catholicos ranks second after the Patriarch within the Syrian Orthodox Church hierarchy. He is elected only by the Metropolitans under the jurisdiction of the Catholicate See. They must obey him, so must the priests, deacons and all the people within the Syrian Orthodox Archdioceses in India. At his ordination, he is proclaimed: Mor Baselius... (his personal name is added here). His name shall be proclaimed throughout the archdioceses in India during the Holy Mass and canonical prayers, after the name of the Patriarch and preceding the name of the Archdiocese Metropolitan. His name should be mentioned also at every Syrian church where he attends prayer. His title is: His Beatitude Mor Baselius... Catholicos of the East and Metropolitan of Malankara..
5. Web site: Catholicate of the East . syriacchristianity.info. 2022-04-24. "In 2002 the office of the Maphrianate was renamed ‘Catholicos of India’ in accordance with its actual jurisdiction".