That's exactly what I mean. What is, and isn't, a door? What is, and isn't, a wheel?

Are treads a type of wheel? Are sliding doors, doors? What about a sliding window on a slightly smaller frame? Are rotating doors are doors, but not open doors? Are bearings and rotors wheels? Are gears wheels? Is a log a wheel, and if not, then if you replace a car's tires with similarly shaped and sized logs then are those wheels?

Is a valve a door? What about a very large, flat shaped valve that looks like a door? Is a swinging door a door or a wooden valve?