cathedral
Concise Oxford English Dictionary © 2008 Oxford University Press:
cathedral/kəˈθiːdrəl/
▶noun the principal church of a diocese.
word history: The word cathedral was first used in the 13th century as an adjective in the term cathedral church or church cathedral, ‘the church which contains the bishop's throne’. It comes from the Latin word for a seat or throne, cathedra, from Greek kathedra, and is closely related to chair. Its use as a noun to mean the principal church of a diocese dates from the 16th century.
'cathedral' also found in these Oxford entries:

