(BuisnessDictionary.com) What this really translates to is whether there is a measurable gain from getting another unit of something. For example, the marginal utility of a third wiper in the center of the windshield would be zero or very close to zero. It wouldn't help you at all. However, if you started without windshield wipers and added one, the marginal utility of that windshield wiper would be very high. Now you could drive even when it rained, whereas before you couldn't