A good for which the demand decreases when income increases. (p. 85)

A good the demand for which falls as income increases. Table wine and potatoes are common examples in the Western world.

a good for which demand decreases when income rises and increases when income falls.

a good the consumption of which falls as income rises

In consumer theory, an inferior good is a good that decreases in demand when the consumer's income rises, unlike normal goods, for which the opposite is observed. Inferiority, in this sense, is an observable fact rather than a statement about the quality of the good. As a rule, surfeit is easily achieved with such goods, and as more costly substitutes that offer more pleasure or at least variety become available, the use of the inferior goods diminishes.