What is a Catholic Church? Here are some definitions.
Noun
The Catholic Church, which consists of 23 particular churches in full communion with the Pope as the Bishop of Rome.
Literally "universal church", the whole body of Christendom, especially before the division into Western and Eastern churches.
Any of the independent Catholic Churches, such as the Old Catholic Church, the Polish National Catholic Church, or the Orthodox Catholic Church.
Any Christian denomination that identifies explicitly as "Catholic" based on its affirmation of the Nicene Creed, such as any of the Anglican Churches.