Giffen good

Giffen good
A Giffen good is an extreme type of inferior good. The negative income effect of changes in price of a Giffen good is actual stronger than the substitution effect.

Giffen good
An increase in income results in a fall in demand for the good. A Giffen good is an extreme form of inferior good. It arises because the income effect is opposite to and outweighs the substitution effect. ...

Giffen goods
Named after Robert Giffen (1837-1910), a good for which demand increases as its price rises. But such goods may not exist in the real world.
Gilts ...

Giffen good - A good that is so inferior and so heavily consumed at low incomes that the demand for it rises when its price rises.

GIFFEN GOOD: A rare type of good seldom seen in the real world, in which a change in price causes quantity demanded to change in the same direction (in violation of the law of demand).

Giffen Good
A consumer good for which demand rises when the price increases, and demand falls when the price decreases.

However, despite years of searching, no generally agreed upon example of a good that has an upward sloping demand curve has been found (also known as a giffen good). Non-economists sometimes think that this would not be the case for certain goods.

See also: Inferior good, Income effect, Substitution, Substitution effect, Elasticity