Disc-ness of cylinders

Topic:
Cylinder
A coin is a disc, and an uncooked piece of spaghetti is a cylinder. If you think about it, however, a coin is also a cylinder and an uncooked piece of spaghetti is also a disc. Most people would say that the coin is more disc-like and the spaghetti more cylinder-like. Can you devise a measure of disc-ness that allows you to order cylinders in order of disc-ness ? What question could / would you put to your students based on this applet ?