Determining the elasticity of Hicksian Demands
Let variable $y$ be determined as a function of variable $x$: $y=f(x)$.

Then the "$x$-elasticity of $y$" is computed as $$\frac{\partial y}{\partial x}\frac{x}{y}.$$

We are used to seeing the "price-elasticity of demand" where $y$ is the quantity demanded, $f$ is the Marshallian demand function, and $x$ is the price. But the same concept can be applied more generally.

For example, if $x$ is income, $y$ is quantity, and $f$ is the Hicksian demand function then we could compute the "income elasticity of Hicksian demand" using the above formula.