Water glass is a distinct nomenclature in the restaurant business (in which I spent too many years) as pointed out by several folks here. A table setting always included a water glass (breakfast, lunch, or dinner). And in formal dinner settings there would be a water glass and a wine glass (turned upside-down, of course, so as not to collect dust, and they better be spotless, and don't ice them too soon or two late, and...too many years, like I said [sigh-e]).