What do you consider a "power user" in the context of online communities?

Pretty much every news story about the Reddit situation that also touches on migration to other services throws out "power user" as distinct from "mods" as though it's an established term with a clear definition.

As far as I'm concerned, it's not. And a search on the term shows wildly different definitions, from X amount of karma, to users whose posts are upvoted simply by virtue of their user name, to people who actually post instead of lurking or commenting.

If after a decade on Reddit I don't understand the term, I can't imagine what it means to the layperson and thus fail to see the utility of the term in news stories. I can't fix journalists using the term, but it would be nice to at least learn what others understand it to mean.