It's a Thing

There are a few words and phrases I know of that name the category of which they are a member.

“Noun”, for instance - the word “noun” is a noun. 

Then of course, the phrase “figure of speech” is itself a figure of speech. Others may disagree, but I also think the phrase “dog whistle” is itself a dog whistle.

Lately it has come to my attention that there are some new phrases using the word “thing” like “I didn’t even know that is a thing” or “Is that even a thing?” “Thing” in this context as best I can tell means “phenomenon” (which comes from the Greek meaning “thing” or actually, “thing appearing to view”). So using “thing” to replace “phenomenon” is now a thing, I guess.

I’m on the lookout for more examples. In the meantime, I wonder if there is a name for the phenomenon of category names that are themselves members of that category, since, you know, it seems to be a thing.