An exceptional demand curve is one that slopes

In standard microeconomic theory, the Law of Demand states that there is an inverse relationship between price and quantity demanded, resulting in a demand curve that slopes downward to the right [1]. However, an 'exceptional demand curve' refers to cases where this law is violated. For certain goods, such as Giffen goods or Veblen goods, the demand curve slopes upward to the right [1]. This means that as the price of the commodity increases, the quantity demanded also increases, defying the typical negative slope. Giffen goods are often inferior staples where the income effect outweighs the substitution effect, while Veblen goods are luxury items where higher prices enhance their status appeal. Consequently, while a normal demand curve is downward-sloping, an exceptional one is characterized by a positive slope moving upward to the right [2].

Sources

1. [1] Microeconomics (NCERT class XII 2025 ed.) > Chapter 2: Theory of Consumer Behaviour > Derivation of Demand Curve in the Case of a Single Commodity (Law of Diminishing Marginal Utility) > p. 10
2. [2] Microeconomics (NCERT class XII 2025 ed.) > Chapter 2: Theory of Consumer Behaviour > Derivation of Demand Curve in the Case of a Single Commodity (Law of Diminishing Marginal Utility) > p. 11