Now, pot roast is occasionally a thing this side of the pond too, but not really a very big one. It’s not a classic, like-grandma-made thing which we all remember fondly. But I might just risk sticking my head above the parapet though and venturing to suggest that if you’re “pot roasting” something, you do in a pot? Otherwise you’re doing something which may very well be absolutely delicious, but isn’t “pot” roasting?
If you’re going down that rabbit hole, a “pot” is “a container, typically rounded or cylindrical and of ceramic ware or metal, used for storage or cooking”, so practically anything you cook it in would qualify. However, pot roast is specifically a roast cooked in a covered container, so that it retains moisture and becomes more tender as it is slow-cooked. If you slow-roast a piece of beef in a covered container (whether it’s covered by a lid or by being wrapped in foil), I would submit that it counts as a “pot roast”.
For the roast prepared in an open skillet that Ukulele Ike described to count as a pot roast, you’d have to go back to the super-vague definition of “pot” that I quoted, though.
Now I want roast beef. Nicely browned, then slow-roasted in a dutch oven with onions and garlic, served with horseradish and crusty bread.
Discussing pot roast, what makes it “Yankee”? Seems like I hear it described that way lately - from “Blondie” to a friend of mine. My friend suggested it is made w/ root vegetables, but if it didn’t have taters and carrots, it wouldn’t be pot roast, would it?
So, pot roast w/ just taters and carrots is just plain old, whereas toss a parsnip in there and it is Yankee?
Yeah, to me a pot roast is something that is, yes, done in a pot (i.e. a covered cooking vessel of some sort), and something that is often done on the stovetop (not just in the oven like your typical braise. But either way is perfectly fine. But that’s one of the nice things about a pot roast, is that you can cook it on top of a flat heat source, and you don’t require an oven.) Otherwise, if it’s uncovered, it’s just “roast” to me.
Roasting originally meant rotating (basically the same word) next to a fire, but now means - essentially - baking. So I guess I must concede that the terminology is not immutable. But this is a bit more descriptive; if “oven roasting” needs to be in an oven, “pot roasting” probably needs to be in a pot?
That said, in a food culture where “pot roast” refers to a dish rather than just a technique, I get it. Toast doesn’t stop being toast because you use a grill (that’s what we call a broiler, I think) rather than a toaster.
Yeah, no, it’s certainly moved on from just a description of a technique. I mean, at the grocery store, there are simply cuts of meat called “pot roast,” so the definition has expanded to the raw ingredient itself. I assume (and it looks like) most of the time this is some sort of chuck/shoulder roast cut, but I don’t know whether the term is policed that finely, or it’s just a way to market any kind of cut of beef that is suitable to a low-and-slow, moist heat cooking method.
I would say that a “Yankee pot roast: a la “Blondie” is just a pot roast of chuck beef with potatoes, onions, celery, and carrots. Maybe turnip or rutabaga.
I cook my pot roast (after thoroughly searing the crust) in an enameled cast iron dutch oven. Half the veg at the beginning so they cook down into the sauce, the other half towards the end so you get nice flavor & color. Pot roast is done when the meat is no longer sliceable. 
Damn near spoon-able.
WAG: To turn a recipe Yankee, add something that a non-Yankee would not be willing to add, or wouldn’t even think of. Only works when you consider the pre-internet and maybe even pre-air-travel world. Now, most local specialties are well known everywhere.