Cross elasticity of demand
In economics, the cross (or cross-price) elasticity of demand (XED) measures the effect of changes in the price of one good on the quantity demanded of another good. This reflects the fact that the quantity demanded of good is dependent on not only its own price (price elasticity of demand) but also the price of other "related" good.
Source: Wikipedia — Cross elasticity of demand (CC BY-SA 4.0)