Wiktionary
n. (context economics English) a good that makes up a larger proportion of consumption as income rises; having income elasticity greater than one.
Wikipedia
Superior goods make up a larger proportion of consumption as income rises, and therefore are a type of normal goods in consumer theory. Such a good must possess two economic characteristics: it must be scarce, and, along with that, it must have a high price. The scarcity of the good can be natural or artificial; however, the general population (i.e., consumers) must recognize the good as distinguishably better. Possession of such a good usually signifies " superiority" in resources, and usually is accompanied by prestige.
The prestige-value of some superior goods is so high that a price decline would lower demand; these are the fabled Veblen goods.
The income elasticity of a superior good is above one by definition, because it raises the expenditure share as income rises. A superior good also may be a luxury good that is not purchased at all below a certain level of income. Examples would include smoked salmon and caviar, and most other delicacies. On the other hand, superior goods may have a wide quality distribution, such as wine and holidays; however, though the number of such goods consumed may stay constant even with rising wealth, the level of spending will go up, to secure a better experience.