What is the prefix that designates largest diocese in a province?

There isn't a specific prefix that designates the largest diocese in a province. The term "largest" can be interpreted in different ways:

* Largest by area: This would depend on the geographic size of the diocese.

* Largest by population: This would depend on the number of people living within the diocese.

* Largest by number of churches: This would depend on the number of churches within the diocese.

While there is no specific prefix for the largest diocese, Archdiocese is a title often given to larger and more important dioceses, but it isn't necessarily assigned based on size. Other factors, such as historical significance and political influence, can also play a role in the designation of an archdiocese.