>Being the seat of a bishop is what a cathedral is.

It's what cathedral's etymology is.

Words are defined by how they're used, not their etymology. Most people just use the word to mean any large church.

In fact, from dictionary.com: (2) (in nonepiscopal denominations) any of various important churches.

Also: Following the Protestant Reformation, the Christian church in several parts of Western Europe, such as Scotland, the Netherlands, certain Swiss Cantons and parts of Germany, adopted a Presbyterian polity that did away with bishops altogether. Where ancient cathedral buildings in these lands are still in use for congregational worship, they generally retain the title and dignity of "cathedral", maintaining and developing distinct cathedral functions, but void of hierarchical supremacy.

The term "cathedral" actually carries no implication as to the size or ornateness of the building. Nevertheless, most cathedrals are particularly impressive edifices. Thus, the term "cathedral" is often applied colloquially to any large and impressive church, regardless of whether it functions as a cathedral, such as the Crystal Cathedral in California or the Arctic Cathedral in Tromsø, Norway.

> It's what cathedral's etymology is. Words are defined by how they're used, not their etymology.

Sure, but we're talking a Catholic church here, and for Catholics, it's not just the etymology—it's the currently used definition as well.

Let me guess, you live in an area where most people are catholic? I'd bet that most protestants have never heard of that particular definition. Of course the reporter should still have gotten it right, but it's easy to see why it's less obvious to some people than others.

Not only they might have not heard that, but they also use the word with another, looser, definition.