<P> The specification above is incomplete, because for any object or system the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal . Accordingly, isothermal compressibility is defined: </P> <Dl> <Dd> β T = − 1 V (∂ V ∂ p) T (\ displaystyle \ beta _ (T) = - (\ frac (1) (V)) \ left ((\ frac (\ partial V) (\ partial p)) \ right) _ (T)) </Dd> </Dl> <Dd> β T = − 1 V (∂ V ∂ p) T (\ displaystyle \ beta _ (T) = - (\ frac (1) (V)) \ left ((\ frac (\ partial V) (\ partial p)) \ right) _ (T)) </Dd> <P> where the subscript T indicates that the partial differential is to be taken at constant temperature . </P>

The reciprocal of coefficient of compressibility is known as