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