Cheese Fries are French fries — waffle, straight or steak cut — covered with cheese, usually in the form of a cheese sauce or melted processed cheese.
Fans, though, say the proper way these should be prepared is with hot, golden-brown, crispy thick cut steak fries, sprinkled generously with grated cheese (a combination of American cheddar and American-style mozzarella), and popped under the broiler (aka grill in the UK) until the cheese melts. They should be served with ranch dressing on the side as a dip, and optionally, bacon bits to garnish.
They are available pretty much all over America.
At places such as White Castle, you just ask for a “cheese fry.”