Frappe to me has always meant one of those fancy ice coffee things.
I was making milk shakes in mums cafe from the 70’s and it was always milk, topping and a scoop of vanilla ice cream and made in a milkshake mixer.
OKay- we need to stop lumping ALL of New England into this mess. 
I live on an island smack-dab on the middle of the Maine coast. I had never even HEARD of a “frappe” until I was more than 25 years old and went to work at an ice cream shop which was owned by a woman from Massachusetts, so let’s first clarify that in fact, people in ALL areas of Maine DO NOT use the term “frappe”. I have always known the frozen concoction of milk+ice cream (plus syrup) to be a MILK SHAKE. Eateries in Southern Maine (which we can also refer to as the Northern Massachusetts Annex) seem to use the term “frappe” occasionally, which i can only assume was brought in by visiting folks from MA, or listed by restaurant owners to amuse the tourists coming from Boston. But I can assure you that at least here in Hancock County, on the cusp between Mid-Coast Maine and Downeast Maine, the default term for ice cream+milk is a MILKSHAKE. 
Still arguing after 14 years? Cripes, people.
If you order a milkshake and they bring you something without ice cream in it, you should be allowed to sue for emotional distress.
Great. Someone had to resurrect this and remind me that I once made a “My Milkshake” reference. :smack: