Thanks for an interesting topic, mumu. "Roast" is not the only cooking term that inspires ambiguity. A tagine, for example, can be either the the North African cooking vessel or the dish that is cooked in it, and a "dish", of course can be the vessel in which a meal is served or cooked or the meal itself.
As everyone has said, roasting is dry heating, and the product of this process. A pot roast, however, is the product of moist heating, but the process is called braising (if you add any moisture. I still consider it braising even if you don't, since the meat is cooked in the steam from the moisture liberated by the meat and veggies) not pot roasting. A broiler can be a chicken of about 5 lbs or so (as opposed to a "fryer"), and again, you can broil a "broiler" in a broiler, the thingy under the stove which will take also tender cuts of meat or your creme brule, if you don't have a flame thrower. I personally dislike this form of cooking. Bending down is easy. getting up again is not.
I agree with Andy's comment about the abuse of cooking terms by advertisers. The relatively new halogen ovens are often touted for their healthy., "fat free frying". Water free boiling will be next.