What is "marginal utility"

n. (context economics English) The additional utility to a consumer from an additional unit of an economic good.

n. (economics) the amount that utility increases with an increase of one unit of an economic good or service

In economics, utility is the satisfaction or benefit derived by consuming a product, thus the marginal utility of a good or service is the change in the utility from increase or decrease in the consumption of that good or service. Economists sometimes speak of a law of diminishing marginal utility, meaning that the first unit of consumption of a good or service yields more utility than the second and subsequent units, with a continuing reduction for greater amounts. Therefore, the fall in marginal utility as consumption increases is known as diminishing marginal utility. Mathematically, MU>MU>MU......>MU. The marginal decision rule states that a good or service should be consumed at a quantity at which the marginal utility is equal to the marginal cost.